Scanning antenna

ABSTRACT

A liquid crystal panel included in a scanning antenna includes: a TFT substrate including a first dielectric substrate, a TFT supported on the first dielectric substrate, a gate bus line, a source bus line, a patch electrode, and a first alignment film covering the patch electrode; a slot substrate including a second dielectric substrate, a slot electrode formed on a first main surface of the second dielectric substrate and including a slot arranged corresponding to the patch electrode, and a second alignment film covering the slot electrode; and a liquid crystal layer provided between the TFT substrate and the slot substrate and containing a liquid crystal molecule having an isothiocyanate group. The patch electrodes and the slot electrode are each formed of a Cu layer or an Al layer, and the first alignment film and the second alignment film each include a compound having an atomic group forming a coordinate bond with Cu or Al.

TECHNICAL FIELD

The disclosure relates to a scanning antenna, and more particularlyrelates to a scanning antenna and a method for manufacturing thereof inwhich an antenna unit (also referred to as an “element antenna”) has aliquid crystal capacitance (also referred to as a “liquid crystal arrayantenna”).

BACKGROUND ART

Antennas for mobile communication and satellite broadcasting requirefunctions that can change the beam direction (referred to as “beamscanning” or “beam steering”). An antenna (hereinafter referred to as a“scanning antenna”) having such functionality, phased array antennasequipped with antenna units are a known example. However, existingphased array antennas are expensive, which is an obstacle forpopularization as a consumer product. In particular, as the number ofantenna units increases, the cost rises considerably.

Therefore, scanning antennas that utilize the high dielectric anisotropy(birefringence) of liquid crystal materials (including nematic liquidcrystals and polymer dispersed liquid crystals) have been proposed (PTL1 to PTL 5 and NPL 1). Since the dielectric constant of liquid crystalmaterials has a frequency dispersion, in the present specification, thedielectric constant (also referred to as the “dielectric constant formicrowaves”) is particularly denoted as “dielectric constant M(ε_(M))”.

PTL 3 and NPL 1 describe how an inexpensive scanning antenna can beobtained by using liquid crystal display (hereinafter referred to as“LCD”) device technology.

CITATION LIST Patent Literature

-   PTL 1: JP 2007-116573 A-   PTL 2: JP 2007-295044 A-   PTL 3: JP 2009-538565 A-   PTL 4: JP 2013-539949 A-   PTL 5: WO 2015/126550

Non Patent Literature

-   NPL 1: R. A. Stevenson et al., “Rethinking Wireless Communications:    Advanced Antenna Design using LCD Technology”, SID 2015 DIGEST. pp.    827-830.-   NPL 2: M. ANDO et al., “A Radial Line Slot Antenna for 12 GHz    Satellite TV Reception”, IEEE Transactions of Antennas and    Propagation, Vol. AP-33, No. 12, pp. 1347-1353 (1985).

SUMMARY Technical Problem

As described above, although the idea of realizing an inexpensivescanning antenna by applying LCD technology is known, there are nodocuments that specifically describe the structure, the manufacturingmethod, and the driving method of scanning antennas using LCDtechnology.

Accordingly, an object of the disclosure is to provide a scanningantenna which can be mass-manufactured by utilizing existingmanufacturing techniques of LCDs and a manufacturing method thereof.

Solution to Problem

A scanning antenna according to an embodiment of the disclosure is ascanning antenna in which a plurality of antenna units are arranged, thescanning antenna including: a TFT substrate including a first dielectricsubstrate, a plurality of TFTs supported on the first dielectricsubstrate, a plurality of gate bus lines, a plurality of source buslines, a plurality of patch electrodes, and a first alignment filmcovering the plurality of patch electrodes; a slot substrate including asecond dielectric substrate, a slot electrode formed on a first mainsurface of the second dielectric substrate, the slot electrode includinga plurality of slots arranged corresponding to the plurality of patchelectrodes, and a second alignment film covering the slot electrode; aliquid crystal layer provided between the TFT substrate and the slotsubstrate, the liquid crystal layer containing a liquid crystal moleculehaving an isothiocyanate group; and a reflective conductive platedisposed to face a second main surface on an opposite side to the firstmain surface of the second dielectric substrate with a dielectric layerinterposed therebetween, wherein the plurality of patch electrodes andthe slot electrodes are each formed of a Cu layer or an Al layer, andwherein the first alignment film and the second alignment film eachinclude a compound having an atomic group forming a coordinate bond withCu or Al.

In an embodiment, at least one of the first alignment film and thesecond alignment film include an upper layer close to the liquid crystallayer and a lower layer, wherein the compound is contained in the lowerlayer.

A scanning antenna according to another embodiment of the disclosure isa scanning antenna in which a plurality of antenna units are arranged,the scanning antenna including: a TFT substrate including a firstdielectric substrate, a plurality of TFTs supported on the firstdielectric substrate, a plurality of gate bus lines, a plurality ofsource bus lines, a plurality of patch electrodes, and a first alignmentfilm covering the plurality of patch electrodes; a slot substrateincluding a second dielectric substrate, a slot electrode formed on afirst main surface of the second dielectric substrate, the slotelectrode including a plurality of slots arranged corresponding to theplurality of patch electrodes, and a second alignment film covering theslot electrode; a liquid crystal layer provided between the TFTsubstrate and the slot substrate, the liquid crystal layer containing aliquid crystal molecule having an isothiocyanate group; and a reflectiveconductive plate disposed to face a second main surface of a seconddielectric substrate on an opposite side to the first main surface witha dielectric layer interposed therebetween, wherein the plurality ofpatch electrodes and the slot electrodes are each formed of a Cu layeror an Al layer, and wherein between the first alignment film and theplurality of patch electrodes and between the second alignment film andthe slot electrode are each independently provided with a resin layercontaining a compound having an atomic group forming a coordinate bondwith Cu or Al.

In an embodiment, the resin layer includes a cured acrylate.

In an embodiment, the compound has an amide bond and a benzene ring.

In an embodiment, the compound has a molecular weight of less than 1000.

In an embodiment, an insulating layer covering the plurality of patchelectrodes and a further insulating layer covering the slot electrodeare provided.

Advantageous Effects of Disclosure

According to an embodiment of the disclosure, a scanning antenna thatcan be mass-produced using known LCD manufacturing technologies and amethod of manufacturing the scanning antenna is provided.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a cross-sectional view schematically illustrating a portion ofa scanning antenna 1000 according to a first embodiment.

FIG. 2A and FIG. 2B are schematic plan views illustrating a TFTsubstrate 101 and a slot substrate 201 in the scanning antenna 1000,respectively.

FIG. 3A and FIG. 3B are a cross-sectional view and a plane viewschematically illustrating an antenna unit region U of the TFT substrate101, respectively.

FIG. 4A to FIG. 4C are cross-sectional views schematically illustratinga gate terminal section GT, a source terminal section ST, and a transferterminal section PT of the TFT substrate 101, respectively.

FIG. 5 is a diagram illustrating an example of a manufacturing processof the TFT substrate 101.

FIG. 6 is a cross-sectional view schematically illustrating an antennaunit region U and a terminal section IT in the slot substrate 201.

FIG. 7 is a schematic cross-sectional view for illustrating a transfersection in the TFT substrate 101 and the slot substrate 201.

FIG. 8A to FIG. 8C are cross-sectional views illustrating the gateterminal section GT, the source terminal section ST, and the transferterminal section PT, respectively, of a TFT substrate 102 in a secondembodiment.

FIG. 9 is a diagram illustrating an example of a manufacturing processof the TFT substrate 102.

FIG. 10A to FIG. 10C are cross-sectional views illustrating the gateterminal section GT, the source terminal section ST, and the transferterminal section PT, respectively, of a TFT substrate 103 in the thirdembodiment.

FIG. 11 is a diagram illustrating an example of a manufacturing processof the TFT substrate 103.

FIG. 12 is a cross-sectional view for illustrating a transfer section inthe TFT substrate 103 and a slot substrate 203.

FIG. 13A is a schematic plan view of a TFT substrate 104 including aheater resistive film 68, and FIG. 13B is a schematic plan view forillustrating the sizes of slots 57 and patch electrodes 15.

FIG. 14A and FIG. 14B are diagrams illustrating the schematic structureand current distribution of resistance heating structures 80 a and 80 b.

FIG. 15A to FIG. 15C are diagrams illustrating the schematic structureand current distribution of resistance heating structures 80 c to 80 e.

FIG. 16A is a schematic cross-sectional view of the liquid crystal panel100Pa having the heater resistive film 68, and FIG. 16B is a schematiccross-sectional view of the liquid crystal panel 100Pb having the heaterresistive film 68.

FIG. 17 is a view of an equivalent circuit of one antenna unit ofscanning antenna according to an embodiment of the disclosure.

FIGS. 18A to 18C and FIGS. 18E to 18G are diagrams illustrating examplesof waveforms of respective signals used for driving the scanning antennaaccording to an embodiment, FIG. 18D is a diagram illustrating thewaveform of a display signal of an LCD panel driven by dot inversiondriving.

FIGS. 19A to 19E are diagrams illustrating another example of thewaveform of each of the signals used for driving the scanning antenna ofan embodiment.

FIGS. 20A to 20E are diagrams illustrating still another example of thewaveform of each of the signals used for driving the scanning antenna ofan embodiment.

FIG. 21 is a schematic cross-sectional view of the liquid crystal panel100A included in a scanning antenna according to an embodiment of thedisclosure.

FIG. 22 is a schematic cross-sectional view of the liquid crystal panel100B included in a scanning antenna according to an embodiment of thedisclosure.

FIG. 23 is a schematic cross-sectional view of the liquid crystal panel100C included in a scanning antenna according to an embodiment of thedisclosure.

FIG. 24 is a schematic cross-sectional view of the liquid crystal panel100D included in a scanning antenna according to an embodiment of thedisclosure.

FIG. 25A is a schematic diagram illustrating the structure of a knownLCD 900, and FIG. 25B is a schematic sectional view of the LCD panel 900a.

DESCRIPTION OF EMBODIMENTS

Hereinafter, a scanning antenna and a manufacturing method thereofaccording to embodiments of the disclosure will be described withreference to the drawings. In the following description, first, thestructure and manufacturing method of a known TFT-type LCD (hereinafterreferred to as a “TFT-LCD”) will be described. However, the descriptionof matters well-known within the technical field of LCDs may be omitted.For a description of basic LCD technology, please refer to, for example,Liquid Crystals, Applications and Uses, Vol. 1-3 (Editor: BirendaBahadur, Publisher: World Scientific Pub Co Inc), or the like. Forreference, the entire contents of the disclosures of the above documentsare incorporated herein.

A structure and an operation of a transmissive-type TFT-LCD (hereinaftersimply referred to as “LCD”) 900 having normal structure will bedescribed with reference to FIGS. 25A and 25B. Here, an LCD 900 with avertical electric field mode (for example, a TN mode or a verticalalignment mode) in which a voltage is applied in a thickness directionof a liquid crystal layer is provided as an example. The frame frequency(which is typically twice the polarity inversion frequency) of thevoltage applied to the liquid crystal capacitance of the LCD is 240 Hzeven at quad speed driving, and the dielectric constant s of the liquidcrystal layer that serves as the dielectric layer of the liquid crystalcapacitance of the LCD is different from the dielectric constant M(ε_(M)) of microwaves (for example, satellite broadcasting, the Ku band(from 12 to 18 GHz), the K band (from 18 to 26 GHz), and the Ka band(from 26 to 40 GHz)).

As schematically illustrated in FIG. 25A, the transmissive-type LCD 900includes a liquid crystal display panel 900 a, a control circuit CNTL, abacklight (not illustrated), a power supply circuit (not illustrated),and the like. The liquid crystal display panel 900 a includes a liquidcrystal display cell LCC and a driving circuit including a gate driverGD and a source driver SD. The driving circuit may be, for example,mounted on a TFT substrate 910 of the liquid crystal display cell LCC,or all or a part of the driving circuit may be integrated (monolithicintegration) with the TFT substrate 910.

FIG. 25B is a schematic cross-sectional view of a liquid crystal displaypanel (hereinafter referred to as “LCD panel”) 900 a included in the LCD900. The LCD panel 900 a includes the TFT substrate 910, a countersubstrate 920, and a liquid crystal layer 930 provided therebetween.Both the TFT substrate 910 and the counter substrate 920 includetransparent substrates 911 and 921, such as glass substrates. Inaddition to glass substrates, plastic substrates may also be used as thetransparent substrates 911 and 921 in some cases. The plastic substratesare formed of, for example, a transparent resin (for example, polyester)and a glass fiber (for example, nonwoven fabric).

A display region DR of the LCD panel 900 a is configured of pixels Parranged in a matrix. A frame region FR that does not serve as part ofthe display is formed around the display region DR. The liquid crystalmaterial is sealed in the display region DR by a sealing portion (notillustrated) formed surrounding the display region DR. The sealingportion is formed by curing a sealing material including, for example,an ultraviolet curable resin and a spacer (for example, resin beads orsilica beads), and bonds and secures the TFT substrate 910 and thecounter substrate 920 to each other. The spacer in the sealing materialcontrols a gap between the TFT substrate 910 and the counter substrate920, that is, a thickness of the liquid crystal layer 930, to beconstant. To suppress an in-plane variation in the thickness of theliquid crystal layer 930, columnar spacers are formed on light blockingportions (for example, on a wiring line) in the display region DR byusing an ultraviolet curable resin. In recent years, as seen in LCDpanels for liquid crystal televisions and smart phones, a width of theframe region FR that does not serve as part of the display is verynarrow.

In the TFT substrate 910, a TFT 912, a gate bus line (scanning line) GL,a source bus line (display signal line) SL, a pixel electrode 914, anauxiliary capacitance electrode (not illustrated), and a CS bus line(auxiliary capacitance line) (not illustrated) are formed on thetransparent substrate 911. The CS bus line is provided parallel to thegate bus line. Alternatively, the gate bus line of the next stage may beused as the CS bus line (CS on-gate structure).

The pixel electrode 914 is covered with an alignment film (for example,a polyimide film) for controlling the alignment of the liquid crystals.The alignment film is provided so as to be in contact with the liquidcrystal layer 930. The TFT substrate 910 is often disposed on thebacklight side (the side opposite to the viewer).

The counter substrate 920 is often disposed on the observer side of theliquid crystal layer 930. The counter substrate 920 includes a colorfilter layer (not illustrated), a counter electrode 924, and analignment film (not illustrated) on the transparent substrate 921. Sincethe counter electrode 924 is provided in common to a plurality of pixelsP constituting the display region DR, it is also referred to as a commonelectrode. The color filter layer includes a color filter (for example,a red filter, a green filter, and a blue filter) provided for each pixelP, and a black matrix (light shielding layer) for blocking lightunnecessary for display. The black matrix is arranged, for example, soas to block light between the pixels P in the display region DR and atthe frame region FR.

The pixel electrode 914 of the TFT substrate 910, the counter electrode924 of the counter substrate 920, and the liquid crystal layer 930therebetween constitute a liquid crystal capacitance Clc. Individualliquid crystal capacitances correspond to the pixels. To retain thevoltage applied to the liquid crystal capacitance Clc (so as to increasewhat is known as the voltage holding rate), an auxiliary capacitance CSelectrically connected in parallel with the liquid crystal capacitanceClc is formed. The auxiliary capacitance CS is typically composed of anelectrode having the same potential as the pixel electrode 914, aninorganic insulating layer (for example, a gate insulating layer (SiO₂layer)), and an auxiliary capacitance electrode connected to the CS busline. Typically, the same common voltage as the counter electrode 924 issupplied from the CS bus line.

Factors responsible for lowering the voltage (effective voltage) appliedto the liquid crystal capacitance Clc are (1) those based on the CR timeconstant which is the product of the capacitance value C_(Clc) of theliquid crystal capacitance Clc and the resistance value R, and (2)interfacial polarization due to ionic impurities included in the liquidcrystal material and/or the orientation polarization of liquid crystalmolecules. Among these, the contribution of the CR time constant of theliquid crystal capacitance Clc is large, and the CR time constant can beincreased by providing an auxiliary capacitance CS electricallyconnected in parallel with the liquid crystal capacitance Clc. Note thatthe volume resistivity of the liquid crystal layer 930 that serves asthe dielectric layer of the liquid crystal capacitance Clc exceeds theorder of 10¹² Ω·cm in the case of widely used nematic liquid crystalmaterials.

A display signal supplied to the pixel electrode 914 is a display signalthat is supplied to the source bus line SL connected to the TFT 912 whenthe TFT 912 selected by a scanning signal supplied from the gate driverGD to the gate bus line GL is turned on. Accordingly, the TFTs 912connected to a particular gate bus line GL are simultaneously turned on,and at that time, corresponding display signals are supplied from thesource bus lines SL connected to the respective TFTs 912 of the pixels Pin that row. By performing this operation sequentially from the firstrow (for example, the uppermost row of a display surface) to the mth row(for example, the lowermost row of the display surface), one image(frame) is written in the display region DR composed of m rows of pixelsand is displayed. Assuming that the pixels P are arranged in a matrix ofm rows and n columns, at least n source bus lines SL are provided intotal such that at least one source bus line SL corresponds to eachpixel column.

Such scanning is referred to as line-sequential scanning, a time betweenone pixel row being selected and the next pixel row being selected iscalled a horizontal scan period, (1H), and a time between a particularrow being selected and then being selected a second time is called avertical scanning period, (1V), or a frame. Note that, in general, 1V(or 1 frame) is obtained by adding the blanking period to the period m·Hfor selecting all m pixel rows.

For example, when an input video signal is an NTSC signal, 1V (=1 frame)of an existing LCD panel is 1/60 of a second (16.7 milliseconds). TheNTSC signals are interlaced signals, the frame frequency is 30 Hz, andthe field frequency is 60 Hz, but in LCD panels, since it is necessaryto supply display signals to all the pixels in each field, they aredriven with 1V=( 1/60) second (driven at 60 Hz). Note that, in recentyears, to improve the video display characteristics, there are LCDpanels driven at double speed drive (120 Hz drive, 1V=( 1/120 second)),and some LCD panels are driven at quad speed (240 Hz drive, 1V=( 1/240second)) for 3D displays.

When a DC voltage is applied to the crystal layer 930, the effectivevoltage decreases and the luminance of the pixel P decreases. Since theabove-mentioned interface polarization and/or the orientationpolarization contribute to the decrease in the effective voltage, it isdifficult for the auxiliary capacitance CS to prevent the decrease inthe effective voltage completely. For example, when a display signalcorresponding to a particular intermediate gray scale is written intoevery pixel in every frame, the luminance fluctuates for each frame andis observed as flicker. In addition, when a DC voltage is applied to theliquid crystal layer 930 for an extended period of time, electrolysis ofthe liquid crystal material may occur. Furthermore, impurity ionssegregate at one side of the electrode, so that the effective voltagemay not be applied to the liquid crystal layer and the liquid crystalmolecules may not move. To prevent this, the LCD panel 900 a issubjected to so-called AC driving. Typically, frame-reversal driving isperformed in which the polarity of the display signal is inverted everyframe (every vertical scanning period). For example, in existing LCDpanels, the polarity inversion is performed every 1/60 seconds (apolarity inversion cycle is 30 Hz).

In addition, dot inversion driving, line reversal driving, or the likeis performed in order to uniformly distribute the pixels havingdifferent polarities of applied voltages even within one frame. This isbecause it is difficult to completely match the magnitude of theeffective voltage applied to the liquid crystal layer between a positivepolarity and a negative polarity. For example, in a case where thevolume resistivity of the liquid crystal material exceeds the order of10¹² Ω·cm, flicker is hardly recognizable in a case where dot inversionor line reversal driving is performed every 1/60 seconds.

With respect to the scanning signal and the display signal in the LCDpanel 900 a, on the basis of the signals supplied from the controlcircuit CNTL to the gate driver GD and the source driver SD, the gatedriver GD and the source driver SD supply the scanning signal and thedisplay signal to the gate bus line GL and the source bus line SL,respectively. For example, the gate driver GD and the source driver SDare each connected to corresponding terminals provided on the TFTsubstrate 910. The gate driver GD and the source driver SD may bemounted on the frame region FR of the TFT substrate 910 as a driver IC,for example, or may be monolithically formed in the frame region FR ofthe TFT substrate 910.

The counter electrode 924 of the counter substrate 920 is electricallyconnected to a terminal (not illustrated) of the TFT substrate 910 witha conductive portion (not illustrated) known as a transfer therebetween.The transfer is formed, for example, so as to overlap with the sealingportion, or alternatively so as to impart conductivity to a part of thesealing portion. This is done to narrow the frame region FR. A commonvoltage is directly or indirectly supplied to the counter electrode 924from the control circuit CNTL. Typically, the common voltage is alsosupplied to the CS bus line as described above.

Basic Structure of Scanning Antenna

By controlling the voltage applied to each liquid crystal layer of eachantenna unit corresponding to the pixels of the LCD panel and changingthe effective dielectric constant M (CM) of the liquid crystal layer foreach antenna unit, a scanning antenna equipped with an antenna unit thatuses the anisotropy (birefringence index) of a large dielectric constantM (CM) of a liquid crystal material forms a two-dimensional pattern byantenna units with different capacities (corresponding to displaying ofan image by an LCD). An electromagnetic wave (for example, a microwave)emitted from an antenna or received by an antenna is given a phasedifference depending on the electrostatic capacitance of each antennaunit, and gains a strong directivity in a particular direction dependingon the two-dimensional pattern formed by the antenna units havingdifferent electrostatic capacitances (beam scanning). For example, anelectromagnetic wave emitted from an antenna is obtained by integrating,with consideration for the phase difference provided by each antennaunit, spherical waves obtained as a result of input electromagneticwaves entering each antenna unit and being scattered by each antennaunit. It can be considered that each antenna unit functions as a “phaseshifter”. For a description of the basic structure and operatingprinciples of a scanning antenna that uses a liquid crystal material,refer to PTL 1 to PTL 4 as well as NPL 1 and NPL 2. NPL 2 discloses thebasic structure of a scanning antenna in which spiral slots arearranged. For reference, the entire contents of the disclosures of PTL 1to PTL 4 as well as NPL 1 and NPL 2 are incorporated herein.

Note that although the antenna units in the scanning antenna accordingto the embodiments of the disclosure are similar to the pixels of theLCD panel, the structure of the antenna units is different from thestructure of the pixel of the LCD panel, and the arrangement of theplurality of antenna units is also different from the arrangement of thepixels in the LCD panel. A basic structure of the scanning antennaaccording to the embodiments of the disclosure will be described withreference to FIG. 1, which illustrates a scanning antenna 1000 of afirst embodiment to be described in detail later. Although the scanningantenna 1000 is a radial in-line slot antenna in which slots areconcentrically arranged, the scanning antennas according to theembodiments of the disclosure are not limited to this. For example, thearrangement of the slots may be any of various known arrangements. Inparticular, with respect to the slot and/or antenna unit arrangements,the entire disclosure of PTL 5 is incorporated herein by reference.

FIG. 1 is a cross-sectional view schematically illustrating a portion ofthe scanning antenna 1000 of the present embodiment, and schematicallyillustrates a part of the cross-section along the radial direction froma power feed pin 72 (see FIG. 2B) provided near the center of theconcentrically arranged slots.

The scanning antenna 1000 includes a TFT substrate 101, a slot substrate201, a liquid crystal layer LC provided therebetween, and a reflectiveconductive plate 65 opposing the slot substrate 201 with an air layer 54interposed between the slot substrate 210 and the reflective conductiveplate 65. The scanning antenna 1000 transmits and receives microwavesfrom a side closer to the TFT substrate 101.

The TFT substrate 101 includes a dielectric substrate 1 such as a glasssubstrate, a plurality of patch electrodes 15 and a plurality of TFTs 10formed on the dielectric substrate 1. Each patch electrode 15 isconnected to a corresponding TFT 10. Each TFT 10 is connected to a gatebus line and a source bus line.

The slot substrate 201 includes a dielectric substrate 51 such as aglass substrate and a slot electrode 55 formed on a side of thedielectric substrate 51 closer to the liquid crystal layer LC. The slotelectrode 55 includes a plurality of slots 57.

The reflective conductive plate 65 is disposed opposing the slotsubstrate 201 with the air layer 54 interposed between the reflectiveconductive plate 65 and the slot substrate 201. In place of the airlayer 54, a layer formed of a dielectric (for example, a fluorine resinsuch as PTFE) having a small dielectric constant M for microwaves can beused. The slot electrode 55, the reflective conductive plate 65, and thedielectric substrate 51 and the air layer 54 therebetween function as awaveguide 301.

The patch electrode 15, the portion of the slot electrode 55 includingthe slot 57, and the liquid crystal layer LC therebetween constitute anantenna unit U. In each antenna unit U, one patch electrode 15 isopposed to a portion of the slot electrode 55 including one slot 57 witha liquid crystal layer LC interposed therebetween, thereby constitutingthe liquid crystal capacitance. The structure in which the patchelectrode 15 and the slot electrode 55 face each other with the liquidcrystal layer LC interposed therebetween is similar to the structure inwhich the pixel electrode 914 and the counter electrode 924 of the LCDpanel 900 a illustrated in FIG. 25A and FIG. 25B face each other withthe liquid crystal layer 930 interposed therebetween. That is, theantenna unit U of the scanning antenna 1000 and the pixel P of the LCDpanel 900 a have a similar configuration. In addition, the antenna unithas a configuration similar to that of the pixel P in the LCD panel 900a in that the antenna unit has an auxiliary capacitance electricallyconnected in parallel with the liquid crystal capacitance (see FIG. 13Aand FIG. 17). However, the scanning antenna 1000 has many differencesfrom the LCD panel 900 a.

First, the performance required for the dielectric substrates 1 and 51of the scanning antenna 1000 is different from the performance requiredfor the substrate of the LCD panel.

Generally, transparent substrates that are transparent to visible lightare used for LCD panels. For example, glass substrates or plasticsubstrates are used. In reflective LCD panels, since the substrate onthe back side does not need transparency, a semiconductor substrate maybe used in some cases. In contrast to this, it is preferable for thedielectric substrates 1 and 51 used for the antennas to have smalldielectric losses with respect to microwaves (where the dielectrictangent with respect to microwaves is denoted as tan δ_(M)). The tanδ_(M) of the dielectric substrates 1 and 51 is preferably approximatelyless than or equal to 0.03, and more preferably less than or equal to0.01. Specifically, a glass substrate or a plastic substrate can beused. Glass substrates are superior to plastic substrates with respectto dimensional stability and heat resistance, and are suitable forforming circuit elements such as TFTs, a wiring line, and electrodesusing LCD technology. For example, in a case where the materials formingthe waveguide are air and glass, as the dielectric loss of glass isgreater, from the viewpoint that thinner glass can reduce the waveguideloss, it is preferable for the thickness to be less than or equal to 400μm, and more preferably less than or equal to 300 μm. There is noparticular lower limit, provided that the glass can be handled such thatit does not break in the manufacturing process.

The conductive material used for the electrode is also different. Inmany cases, an ITO film is used as a transparent conductive film forpixel electrodes and counter electrodes of LCD panels. However, ITO hasa large tan δ_(M) with respect to microwaves, and as such cannot be usedas the conductive layer in an antenna. The slot electrode 55 functionsas a wall for the waveguide 301 together with the reflective conductiveplate 65. Accordingly, to suppress the transmission of microwaves in thewall of the waveguide 301, it is preferable that the thickness of thewall of the waveguide 301, that is, the thickness of the metal layer (Culayer or Al layer) be large. It is known that in a case where thethickness of the metal layer is three times the skin depth,electromagnetic waves are attenuated to 1/20 (−26 dB), and in a casewhere the thickness is five times the skin depth, electromagnetic wavesare attenuated to about 1/150 (−43 dB). Accordingly, in a case where thethickness of the metal layer is five times the skin depth, thetransmittance of electromagnetic waves can be reduced to 1%. Forexample, for a microwave of 10 GHz, in a case where a Cu layer having athickness of greater than or equal to 3.3 μm and an Al layer having athickness of greater than or equal to 4.0 μm are used, microwaves can bereduced to 1/150. In addition, for a microwave of 30 GHz, in a casewhere a Cu layer having a thickness of greater than or equal to 1.9 μmand an Al layer having a thickness of greater than or equal to 2.3 μmare used, microwaves can be reduced to 1/150. In this way, the slotelectrode 55 is preferably formed of a relatively thick Cu layer or Aulayer. There is no particular upper limit for the thickness of the Culayer or the Al layer, and the thicknesses can be set appropriately inconsideration of the time and cost of film formation. The usage of a Culayer provides the advantage of being thinner than the case of using anAl layer. Relatively thick Cu layers or Al layers can be formed not onlyby the thin film deposition method used in LCD manufacturing processes,but also by other methods such as bonding Cu foil or Al foil to thesubstrate. The thickness of the metal layer, for example, ranges from 2μm to 30 μm. When the thin film deposition methods are used, thethickness of the metal layer is preferably less than or equal to 5 μm.Note that aluminum plates, copper plates, or the like having a thicknessof several mm can be used as the reflective conductive plate 65, forexample.

Since the patch electrode 15 does not configure the waveguide 301 likethe slot electrode 55, a Cu layer or an Al layer can be used that has asmaller thickness than that of the slot electrode 55. However, to avoidlosses caused by heat when the oscillation of free electrons near theslot 57 of the slot electrode 55 induces the oscillation of the freeelectrons in the patch electrode 15, it is preferable that theresistance be low. From the viewpoint of mass production, it ispreferable to use an Al layer rather than a Cu layer, and the thicknessof the Al layer is preferably greater than or equal to 0.3 μm and lessthan or equal to 2 μm, for example.

In addition, an arrangement pitch of the antenna units U is considerablydifferent from that of a pixel pitch. For example, considering anantenna for microwaves of 12 GHz (Ku band), the wavelength λ is 25 mm,for example. Then, as described in PTL 4, since the pitch of the antennaunit U is less than or equal to λ/4 and/or less than or equal to λ/5,the arrangement pitch becomes less than or equal to 6.25 mm and/or lessthan or equal to 5 mm. This is ten times greater than the pixel pitch ofthe LCD panel. Accordingly, the length and width of the antenna unit Uare also roughly ten times greater than the pixel length and width ofthe LCD panel.

Of course, the arrangement of the antenna units U may be different fromthe arrangement of the pixels in the LCD panel. Herein, although anexample is illustrated in which the antenna units U are arranged inconcentric circles (for example, refer to JP 2002-217640 A), the presentdisclosure is not limited thereto, and the antenna units may be arrangedin a spiral shape as described in NPL 2, for example. Furthermore, theantenna units may be arranged in a matrix as described in PTL 4.

The properties required for the liquid crystal material of the liquidcrystal layer LC of the scanning antenna 1000 are different from theproperties required for the liquid crystal material of the LCD panel. Inthe LCD panel, a change in a refractive index of the liquid crystallayer of the pixels allows a phase difference to be provided to thepolarized visible light (wavelength of from 380 nm to 830 nm) such thatthe polarization state is changed (for example, the change in therefractive index allows the polarization axis direction of linearlypolarized light to be rotated or the degree of circular polarization ofcircularly polarized light to be changed), whereby display is performed.In contrast, in the scanning antenna 1000 according to the embodiment,the phase of the microwave excited (re-radiated) from each patchelectrode is changed by changing the electrostatic capacitance value ofthe liquid crystal capacitance of the antenna unit U. Accordingly, theliquid crystal layer preferably has a large anisotropy (Δε_(M)) of thedielectric constant M (ε_(M)) with respect to microwaves, and δ_(M) ispreferably small. For example, the Δε_(M) of greater than or equal to 4and the δ_(M) of less than or equal to 0.02 (values of 19 GHz in bothcases) described in SID 2015 DIGEST pp. 824-826 written by M. Witteck etal, can be suitably used. In addition, it is possible to use a liquidcrystal material having a Δε_(M) of greater than or equal to 0.4 and aδ_(M) of less than or equal to 0.04 as described in POLYMERS 55 vol.August issue pp. 599-602 (2006), written by Kuki.

In general, the dielectric constant of a liquid crystal material has afrequency dispersion, but the dielectric anisotropy Δε_(M) formicrowaves has a positive correlation with the refractive indexanisotropy Δn with respect to visible light. Accordingly, it can be saidthat a material having a large refractive index anisotropy Δn withrespect to visible light is preferable as a liquid crystal material foran antenna unit for microwaves. The refractive index anisotropy Δn ofthe liquid crystal material for LCDs is evaluated by the refractiveindex anisotropy for light having a wavelength of 550 nm. Here again,when a Δn (birefringence index) is used as an index for light having awavelength of 550 nm, a nematic liquid crystal having a Δn of greaterthan or equal to 0.3, preferably greater than or equal to 0.4, can beused for an antenna unit for microwaves. An has no particular upperlimit. However, since liquid crystal materials having a large Δn tend tohave a strong polarity, there is a possibility that reliability maydecrease. From the viewpoint of reliability, Δn is preferably less thanor equal to 0.4. The thickness of the liquid crystal layer is, forexample, from 1 μm to 500 μm.

Hereinafter, the structure and manufacturing method of the scanningantenna according to the embodiments of the disclosure will be describedin more detail.

First Embodiment

First, a description is given with reference to FIG. 1 and FIGS. 2A and2B. FIG. 1 is a schematic partial cross-sectional view of the scanningantenna 1000 near the center thereof as described above, and FIG. 2A andFIG. 2B are schematic plan views illustrating the TFT substrate 101 andthe slot substrate 201 in the scanning antenna 1000, respectively.

The scanning antenna 1000 includes a plurality of antenna units Uarranged two-dimensionally. In the scanning antenna 1000 exemplifiedhere, the plurality of antenna units are arranged concentrically. In thefollowing description, the region of the TFT substrate 101 and theregion of the slot substrate 201 corresponding to the antenna units Uwill be referred to as “antenna unit region”, and be denoted with thesame reference numeral U as the antenna units. In addition, asillustrated in FIG. 2A and FIG. 2B, in the TFT substrate 101 and theslot substrate 201, a region defined by the plurality oftwo-dimensionally arranged antenna unit regions is referred to as“transmission and/or reception region R1”, and a region other than thetransmission and/or reception region R1 is called a “non-transmissionand/or reception region R2”. A terminal section, a driving circuit, andthe like are provided in the non-transmission and/or reception regionR2.

FIG. 2A is a schematic plan view illustrating the TFT substrate 101 inthe scanning antenna 1000.

In the illustrated example, the transmission and/or reception region R1has a donut-shape when viewed from a normal direction of the TFTsubstrate 101. The non-transmission and/or reception region R2 includesa first non-transmission and/or reception region R2 a located at thecenter of the transmission and/or reception region R1 and a secondnon-transmission and/or reception region R2 b located at the peripheryof the transmission and/or reception region R1. An outer diameter of thetransmission and/or reception region R1, for example, is from 200 mm to1500 mm, and is configured according to a data traffic volume or thelike.

A plurality of gate bus lines GL and a plurality of source bus lines SLsupported by the dielectric substrate 1 are provided in the transmissionand/or reception region R1 of the TFT substrate 101, and the antennaunit regions U are defined by these wiring lines. The antenna unitregions U are, for example, arranged concentrically in the transmissionand/or reception region R1. Each of the antenna unit regions U includesa TFT and a patch electrode electrically connected to the TFT. Thesource electrode of the TFT is electrically connected to the source busline SL, and the gate electrode is electrically connected to the gatebus line GL. In addition, the drain electrode is electrically connectedto the patch electrode.

In the non-transmission and/or reception region R2 (R2 a, R2 b), a sealregion Rs is disposed surrounding the transmission and/or receptionregion R1. A sealing material (not illustrated) is applied to the sealregion Rs. The sealing material bonds the TFT substrate 101 and the slotsubstrate 201 to each other, and also encloses liquid crystals betweenthese substrates 101, 201.

A gate terminal section GT, the gate driver GD, a source terminalsection ST, and the source driver SD are provided outside the sealingregion Rs in the non-transmission and/or reception region R2. Each ofthe gate bus lines GL is connected to the gate driver GD with the gateterminal section GT therebetween. Each of the source bus lines SL isconnected to the source driver SD with the source terminal section STtherebetween. Note that, in this example, although the source driver SDand the gate driver GD are formed on the dielectric substrate 1, one orboth of these drivers may be provided on another dielectric substrate.

Also, a plurality of transfer terminal sections PT are provided in thenon-transmission and/or reception region R2. The transfer terminalsection PT is electrically connected to the slot electrode 55 (FIG. 2B)of the slot substrate 201. In the present specification, the connectionsection between the transfer terminal section PT and the slot electrode55 is referred to as a “transfer section”. As illustrated in drawings,the transfer terminal section PT (transfer section) may be disposed inthe seal region Rs. In this case, a resin containing conductiveparticles may be used as the sealing material. In this way, liquidcrystals are sealed between the TFT substrate 101 and the slot substrate201, and an electrical connection can be secured between the transferterminal section PT and the slot electrode 55 of the slot substrate 201.In this example, although a transfer terminal section PT is disposed inboth the first non-transmission and/or reception region R2 a and thesecond non-transmission and/or reception region R2 b, the transferterminal section PT may be disposed in only one of them.

Note that the transfer terminal section PT (transfer section) need notbe disposed in the seal region Rs. For example, the transfer terminalsection PT may be disposed outside the seal region Rs in thenon-transmission and/or reception region R2.

FIG. 2B is a schematic plan view illustrating the slot substrate 201 inthe scanning antenna 1000, and illustrates the surface of the slotsubstrate 201 closer to the liquid crystal layer LC.

In the slot substrate 201, the slot electrode 55 is formed on thedielectric substrate 51 extending across the transmission and/orreception region R1 and the non-transmission and/or reception region R2.

In the transmission and/or reception region R1 of the slot substrate201, a plurality of slots 57 are formed in the slot electrode 55. Theslots 57 are formed corresponding to the antenna unit region U on theTFT substrate 101. For the plurality of slots 57 in the illustratedexample, a pair of slots 57 extending in directions substantiallyorthogonal to each other are concentrically disposed so that a radialinline slot antenna is configured. Since the scanning antenna 1000includes slots that are substantially orthogonal to each other, thescanning antenna 1000 can transmit and receive circularly polarizedwaves.

A plurality of terminal sections IT of the slot electrode 55 areprovided in the non-transmission and/or reception region R2. Theterminal section IT is electrically connected to the transfer terminalsection PT (FIG. 2A) of the TFT substrate 101. In this example, theterminal section IT is disposed within the seal region Rs, and iselectrically connected to a corresponding transfer terminal section PTby a sealing material containing conductive particles.

In addition, the power feed pin 72 is disposed on a rear surface side ofthe slot substrate 201 in the first non-transmission and/or receptionregion R2 a. The power feed pin 72 allows microwaves to be inserted intothe waveguide 301 constituted by the slot electrode 55, the reflectiveconductive plate 65, and the dielectric substrate 51. The power feed pin72 is connected to a power feed device 70. Power feeding is performedfrom the center of the concentric circle in which the slots 57 arearranged. The power feed method may be either a direct coupling powerfeed method or an electromagnetic coupling method, and a known powerfeed structure can be utilized.

In FIG. 2A and FIG. 2B, an example is illustrated in which the sealregion Rs is provided so as to surround a relatively narrow regionincluding the transmission and/or reception region R1, but thearrangement of the seal region Rs is not limited to this. In particular,the seal region Rs provided outside the transmission and/or receptionregion R1 may be provided nearby the side of the dielectric substrate 1and/or the dielectric substrate 51, for example, so as to maintain acertain distance or more from the transmission and/or reception regionR1. Of course, the terminal section and the driving circuit, forexample, that are provided in the non-transmission and/or receptionregion R2 may be formed outside the seal region Rs (that is, the sidewhere the liquid crystal layer is not present). By forming the sealregion Rs at a position separated from the transmission and/or receptionregion R1 by a certain distance or more, it is possible to prevent theantenna characteristics from deteriorating due to the influence ofimpurities (in particular, ionic impurities) contained in the sealingmaterial (in particular, a curable resin).

In the following, each component of the scanning antenna 1000 will bedescribed in detail with reference to drawings.

Structure of TFT Substrate 101

Antenna Unit Region U

FIG. 3A and FIG. 3B are a cross-sectional view and a plane viewschematically illustrating the antenna unit region U of the TFTsubstrate 101, respectively.

Each of the antenna unit regions U includes a dielectric substrate (notillustrated), a TFT 10 supported by the dielectric substrate, a firstinsulating layer 11 covering the TFT 10, a patch electrode 15 formed onthe first insulating layer 11 and electrically connected to the TFT 10,and a second insulating layer 17 covering the patch electrode 15. TheTFT 10 is disposed, for example, at or near an intersection of the gatebus line GL and the source bus line SL.

The TFT 10 include a gate electrode 3, an island-shaped semiconductorlayer 5, a gate insulating layer 4 disposed between the gate electrode 3and the semiconductor layer 5, a source electrode 7S, and a drainelectrode 7D. The structure of the TFT 10 is not particularly limited toa specific structure. In this example, the TFT 10 is a channel etch-typeTFT having a bottom gate structure.

The gate electrode 3 is electrically connected to the gate bus line GL,and a scanning signal is supplied via the gate bus line GL. The sourceelectrode 7S is electrically connected to the source bus line SL, and adata signal is supplied via the source bus line SL. The gate electrode 3and the gate bus line GL may be formed of the same conductive film (gateconductive film). The source electrode 7S, the drain electrode 7D, andthe source bus line SL may be formed from the same conductive film(source conductive film). The gate conductive film and the sourceconductive film are, for example, metal films. In the presentspecification, layers formed using a gate conductive film may bereferred to as “gate metal layers”, and layers formed using a sourceconductive film may be referred to as “source metal layers”.

The semiconductor layer 5 is disposed overlapping with the gateelectrode 3 with the gate insulating layer 4 interposed therebetween. Inthe illustrated example, a source contact layer 6S and a drain contactlayer 6D are formed on the semiconductor layer 5. The source contactlayer 6S and the drain contact layer 6D are disposed on both sides of aregion where a channel is formed in the semiconductor layer 5 (channelregion). The semiconductor layer 5 may be an intrinsic amorphous silicon(i-a-Si) layer, and the source contact layer 6S and the drain contactlayer 6D may be n⁺ type amorphous silicon (n⁺-a-Si) layers.

The source electrode 7S is provided in contact with the source contactlayer 6S and is connected to the semiconductor layer 5 with the sourcecontact layer 6S interposed therebetween. The drain electrode 7D isprovided in contact with the drain contact layer 6D and is connected tothe semiconductor layer 5 with the drain contact layer 6D interposedtherebetween.

The first insulating layer 11 includes a contact hole CH1 that at leastreaches the drain electrode 7D of the TFT 10.

The patch electrode 15 is provided on the first insulating layer 11 andwithin the contact hole CH1, and is in contact with the drain electrode7D in the contact hole CH1. The patch electrode 15 includes a metallayer. The patch electrode 15 may be a metal electrode formed only froma metal layer. The material of the patch electrode 15 may be the same asthat of the source electrode 7S and the drain electrode 7D. However, athickness of the metal layer in the patch electrode 15 (a thickness ofthe patch electrode 15 when the patch electrode 15 is a metal electrode)is set to be greater than thicknesses of the source electrode 7S and thedrain electrode 7D. The thickness of the metal layer in the patchelectrode 15 is set to, for example, greater than or equal to 0.3 μmwhen it is formed of an Al layer.

A CS bus line CL may be provided using the same conductive film as thatof the gate bus line GL. The CS bus line CL may be disposed overlappingwith the drain electrode (or extended portion of the drain electrode) 7Dwith the gate insulating layer 4 interposed therebetween, and mayconstitute the auxiliary capacitance CS having the gate insulating layer4 as a dielectric layer.

An alignment mark (for example, a metal layer) 21 and a base insulatingfilm 2 covering the alignment mark 21 may be formed at a position closerto the dielectric substrate than a position of the gate bus line GL. Thealignment mark 21 is used as follows. When manufacturing m TFTsubstrates from one glass substrate, in a case where the number ofphotomasks is n (where n<m), for example, it is necessary to performeach exposure process multiple times. In this way, when the number (n)of photomasks is less than the number (m) of TFT substrates 101manufactured from one glass substrate 1, the alignment mark 21 can beused for alignment of the photomasks. The alignment mark 21 may beomitted.

In the present embodiment, the patch electrode 15 is formed in a layerdifferent from the source metal layer. This provides the advantagesdescribed below.

Since the source metal layer is typically formed using a metal film, itis conceivable to form a patch electrode in the source metal layer.However, it is preferable that the patch electrode have a low resistanceto the extent that the vibration of electrons is not hindered. The patchelectrode is formed of a comparatively thick Al layer having a thicknessof greater than or equal to 0.3 μm, for example. From the viewpoint ofantenna performance, it is preferable that the patch electrode be thick.Depending on the configuration of the TFT, however, when a patchelectrode having a thickness exceeding 1 μm is formed in the sourcemetal layer, a problem arises in that the desired patterning accuracycannot be obtained. For example, there may be a problem that the gapbetween the source electrode and the drain electrode (corresponding tothe channel length of the TFT) cannot be controlled with high accuracy.In contrast, in the present embodiment, since the patch electrode 15 isformed separately from the source metal layer, the thickness of thesource metal layer and the thickness of the patch electrode 15 can becontrolled independently. This allows the controllability for formingthe source metal layer to be secured and a patch electrode 15 having adesired thickness to be formed.

In the present embodiment, the thickness of the patch electrode 15 canbe set with a high degree of freedom separately from the thickness ofthe source metal layer. Note that since the size of the patch electrode15 needs not be controlled as strictly as the source bus line SL or thelike, it is acceptable for the line width shift (deviation from thedesign value) to be increased by thickening the patch electrode 15. Notethat a case where the thickness of the patch electrode 15 is equal tothe thickness of the source metal layer is not excluded.

The patch electrode 15 may include a Cu layer or an Al layer as a mainlayer. A performance of the scanning antenna correlates with an electricresistance of the patch electrode 15, and a thickness of the main layeris set so as to obtain a desired resistance. In terms of the electricresistance, there is a possibility that the thickness of the patchelectrode 15 can be made thinner in the Cu layer than in the Al layer.

Gate Terminal Section GT, Source Terminal Section ST, and TransferTerminal Section PT

FIG. 4A to FIG. 4C are cross-sectional views schematically illustratingthe gate terminal section GT, the source terminal section ST, and thetransfer terminal section PT, respectively.

The gate terminal section GT includes a gate bus line GL formed on thedielectric substrate, an insulating layer covering the gate bus line GL,and a gate terminal upper connection section 19 g. The gate terminalupper connection section 19 g is in contact with the gate bus line GLwithin the contact hole CH2 formed in the insulating layer. In thisexample, the insulating layer covering the gate bus line GL includes thegate insulating layer 4, the first insulating layer 11 and the secondinsulating layer 17 in that order from the dielectric substrate side.The gate terminal upper connection section 19 g is, for example, atransparent electrode formed of a transparent conductive film providedon the second insulating layer 17.

The source terminal section ST includes the source bus line SL formed onthe dielectric substrate (here, on the gate insulating layer 4), theinsulating layer covering the source bus line SL, and the sourceterminal upper connection section 19 s. The source terminal upperconnection section 19 s is in contact with the source bus line SL withinthe contact hole CH3 formed in the insulating layer. In this example,the insulating layer covering the source bus line SL includes the firstinsulating layer 11 and the second insulating layer 17. The sourceterminal upper connection section 19 s is, for example, a transparentelectrode formed of a transparent conductive film provided on the secondinsulating layer 17.

The transfer terminal section PT includes a patch connection section 15p formed on the first insulating layer 11, the second insulating layer17 covering the patch connection section 15 p, and a transfer terminalupper connection section 19 p. The transfer terminal upper connectionsection 19 p is in contact with the patch connection section 15 p withina contact hole CH4 formed in the second insulating layer 17. The patchconnection section 15 p is formed of the same conductive film as that ofthe patch electrode 15. The transfer terminal upper connection section(also referred to as an upper transparent electrode) 19 p is, forexample, a transparent electrode formed of a transparent conductive filmprovided on the second insulating layer 17. In the present embodiment,the upper connection sections 19 g, 19 s, and 19 p for the respectiveterminal sections are formed of the same transparent conductive film.

In the present embodiment, it is advantageous that the contact holesCH2, CH3, and CH4 of the respective terminal sections can besimultaneously formed by the etching process after the formation of thesecond insulating layer 17. The detailed manufacturing process thereofwill be described later.

TFT Substrate 101 Manufacturing Method

As an example, the TFT substrate 101 can be manufactured by thefollowing method. FIG. 5 is a diagram exemplifying the manufacturingprocess of the TFT substrate 101.

First, a metal film (for example, a Ti film) is formed on a dielectricsubstrate and patterned to form an alignment mark 21. A glass substrate,a plastic substrate (resin substrate) having heat resistance, or thelike can be used as the dielectric substrate, for example. Next, thebase insulating film 2 is formed so as to cover the alignment mark 21.An SiO₂ film is used as the base insulating film 2.

Subsequently, a gate metal layer including the gate electrode 3 and thegate bus line GL is formed on the base insulating film 2.

The gate electrode 3 can be formed integrally with the gate bus line GL.Here, a non-illustrated gate conductive film (with a thickness ofgreater than or equal to 50 nm and less than or equal to 500 nm) isformed on the dielectric substrate by a sputtering method or the like.Next, the gate conductive film is patterned to obtain the gate electrode3 and the gate bus line GL. The material of the gate conductive film isnot particularly limited to a specific material. A film containing ametal such as aluminum (Al), tungsten (W), molybdenum (Mo), tantalum(Ta), chromium (Cr), titanium (Ti), or copper (Cu), an alloy thereof, oralternatively a metal nitride thereof can be appropriately used. Here,as a gate conductive film, a layered film is formed by layering MoN(having a thickness of 50 nm, for example), Al (having a thickness of200 nm, for example), and MoN (having a thickness of 50 nm, for example)in this order.

Next, the gate insulating layer 4 is formed so as to cover the gatemetal layer. The gate insulating layer 4 can be formed by a CVD methodor the like. As the gate insulating layer 4, a silicon oxide (SiO₂)layer, a silicon nitride (SiNx) layer, a silicon oxynitride (SiOxNy:x>y) layer, a silicon nitride oxide (SiNxOy; x>y) layer, or the like maybe used as appropriate. The gate insulating layer 4 may have a layeredstructure. Here, a SiNx layer (having a thickness of 410 nm, forexample) is formed as the gate insulating layer 4.

Next, the semiconductor layer 5 and a contact layer are formed on thegate insulating layer 4. Here, an intrinsic amorphous silicon film (witha thickness of 125 nm, for example) and an n⁺ type amorphous siliconfilm (with a thickness of 65 nm, for example) are formed in this orderand patterned to obtain an island-shaped semiconductor layer 5 and acontact layer. The semiconductor film used for the semiconductor layer 5is not limited to an amorphous silicon film. For example, an oxidesemiconductor layer may be formed as the semiconductor layer 5. In thiscase, it is not necessary to provide a contact layer between thesemiconductor layer 5 and the source/drain electrodes.

Next, a source conductive film (having a thickness of greater than orequal to 50 nm and less than or equal to 500 nm, for example) is formedon the gate insulating layer 4 and the contact layer, and patterned toform a source metal layer including the source electrode 7S, the drainelectrode 7D, and the source bus line SL. At this time, the contactlayer is also etched, and the source contact layer 6S and the draincontact layer 6D separated from each other are formed.

The material of the source conductive film is not particularly limitedto a specific material. A film containing a metal such as aluminum (Al),tungsten (W), molybdenum (Mo), tantalum (Ta), chromium (Cr), titanium(Ti), or copper (Cu), an alloy thereof, or alternatively a metal nitridethereof can be appropriately used. Here, as a source conductive film, alayered film is formed by layering MoN (having a thickness of 30 nm, forexample), Al (having a thickness of 200 nm, for example), and MoN(having a thickness of 50 nm, for example) in this order. Instead, as asource conductive film, a layered film may be formed by layering Ti(having a thickness of 30 nm, for example), MoN (having a thickness of30 nm, for example), Al (having a thickness of 200 nm, for example), andMoN (having a thickness of 50 nm, for example) in this order.

Here, for example, a source conductive film is formed by a sputteringmethod and the source conductive film is patterned by wet etching(source/drain separation). Thereafter, a portion of the contact layerlocated on the region that will serve as the channel region of thesemiconductor layer 5 is removed by dry etching, for example, to form agap portion, and the source contact layer 6S and the drain contact layer6D are separated. At this time, in the gap portion, the area around thesurface of the semiconductor layer 5 is also etched (overetching).

Note that, when a layered film in which a Ti film and an Al film layeredin this order is used as a source conductive film, for example, afterpatterning the Al film by wet etching using, for example, an aqueoussolution of phosphoric acid, acetic acid, and nitric acid, the Ti filmand the contact layer (n⁺ type amorphous silicon layer) 6 may besimultaneously patterned by dry etching. Alternatively, it is alsopossible to collectively etch the source conductive film and the contactlayer. However, in the case of simultaneously etching the sourceconductive film, or the lower layer thereof and the contact layer 6, itmay be difficult to control the distribution of the etching amount ofthe semiconductor layer 5 (the amount of excavation of the gap portion)of the entire substrate. In contrast, as described above, in a casewhere etching is performed in an etching step separate from thesource/drain separation and the gap portion formation, the etchingamount of the gap portion can be more easily controlled.

Next, the first insulating layer 11 is formed so as to cover the TFT 10.In this example, the first insulating layer 11 is disposed so as to bein contact with the channel region of the semiconductor layer 5. Inaddition, the contact hole CH1 that at least reaches the drain electrode7D is formed in the first insulating layer 11 by a knownphotolithographic method.

The first insulating layer 11 may be an inorganic insulating layer suchas a silicon oxide (SiO₂) film, a silicon nitride (SiNx) film, a siliconoxynitride (SiOxNy; x>y) film, or a silicon nitride oxide (SiNxOy: x>y)film, for example. Here, as the first insulating layer 11, a SiNx layerhaving a thickness of 330 nm, for example, is formed by a CVD method.

Next, a patch conductive film is formed on the first insulating layer 11and within the contact hole CH1, and this is subsequently patterned. Inthis way, the patch electrode 15 is formed in the transmission and/orreception region R1, and the patch connection section 15 p is formed inthe non-transmission and/or reception region R2. The patch electrode 15is in contact with the drain electrode 7D within the contact hole CH1.Note that, in the present specification, the layer including the patchelectrode 15 and the patch connection section 15 p formed from the patchconductive film may be referred to as a “patch metal layer” in somecases.

The same material as that of the gate conductive film or the sourceconductive film can be used as the material of the patch conductivefilm. However, the patch conductive film is set to be thicker than thegate conductive film and the source conductive film. Accordingly, byreducing the sheet resistance of the patch electrode, the loss resultingfrom the oscillation of free electrons in the patch electrode changingto heat can be reduced. A suitable thickness of the patch conductivefilm is, for example, greater than or equal to 0.3 μm. In a case wherethe thickness of the patch conductive film becomes thinner than this,the sheet resistance becomes greater or equal to 0.10 Ω/sq, and there isa possibility that the loss increases. The thickness of the patchconductive film is, for example, less than or equal to 3 μm, and morepreferably less than or equal to 2 μm. In a case where the thickness isthicker than this, warping of the substrate may occur. In a case wherethe warping is large, problems such as conveyance troubles, chipping ofthe substrate, or cracking of the substrate may occur in the massproduction process.

Here, as a patch conductive film, a layered film (MoN/Al/MoN) is formedby layering MoN (having a thickness of 50 nm, for example), Al (having athickness of 1000 nm, for example), and MoN (having a thickness of 50nm, for example) in this order. Instead, a layered film (MoN/Al/MoN/Ti)may be formed by layering Ti (having a thickness of 50 nm, for example),MoN (having a thickness of 50 nm, for example), Al (having a thicknessof 2000 nm, for example), and MoN (having a thickness of 50 nm, forexample) in this order. Alternatively, instead, a layered film(MoN/Al/MoN/Ti) may be formed by layering Ti (having a thickness of 50nm, for example), MoN (having a thickness of 50 nm, for example), Al(having a thickness of 500 nm, for example), and MoN (having a thicknessof 50 nm, for example) in this order. Alternatively, a layered film(Ti/Cu/Ti) in which a Ti film, a Cu film, and a Ti film are layered inthis order, or a layered film (Cu/Ti) in which a Ti film and a Cu filmare layered in this order may be used.

Next, the second insulating layer (having a thickness of greater than orequal to 100 nm and less than or equal to 300 nm) 17 is formed on thepatch electrode 15 and the first insulating layer 11. The secondinsulating layer 17 is not particularly limited to a specific film, and,for example, a silicon oxide (SiO₂) film, a silicon nitride (SiNx) film,a silicon oxynitride (SiOxNy; x>y) film, a silicon nitride oxide(SiNxOy; x>y) film, or the like can be used as appropriate. Here, as thesecond insulating layer 17, for example, a SiNx layer having a thicknessof 200 nm is formed.

Thereafter, the inorganic insulating films (the second insulating layer17, the first insulating layer 11, and the gate insulating layer 4) areetched collectively by dry etching using a fluorine-based gas, forexample. During the etching, the patch electrode 15, the source bus lineSL, and the gate bus line GL each function as an etch stop. In this way,the contact hole CH2 that at least reaches the gate bus line GL isformed in the second insulating layer 17, the first insulating layer 11,and the gate insulating layer 4, and the contact hole CH3 that at leastreaches the source bus line SL is formed in the second insulating layer17 and the first insulating layer 11. In addition, the contact hole CH4that at least reaches the patch connection section 15 p is formed in thesecond insulating layer 17.

In this example, since the inorganic insulating films are etchedcollectively, side surfaces of the second insulating layer 17, firstinsulating layer 11, and gate insulating layer 4 are aligned on a sidewall of the obtained contact hole CH2, and the side walls of the secondinsulating layer 17 and first insulating layer 11 are aligned on a sidewall of the contact hole CH3. Note that, in the present embodiment, theexpression that “the side surfaces of different two or more layers arealigned” within the contact hole does not only refer to when the sidesurfaces exposed in the contact hole in these layers are flush in thevertical direction, but also includes cases where inclined surfaces suchas continuous tapered shapes are formed. Such a structure can beobtained, for example, by etching these layers using the same mask, oralternatively by using one of these layers as a mask to etch the otherlayer.

Next, a transparent conductive film (having a thickness of greater thanor equal to 50 nm and less than or equal to 200 nm) is formed on thesecond insulating layer 17 and within the contact holes CH2, CH3, andCH4 by a sputtering method, for example. An indium tin oxide (ITO) film,an IZO film, a zinc oxide (ZnO) film or the like can be used as thetransparent conductive film. Here, an ITO film having a thickness of,for example, 100 nm is used as the transparent conductive film.

Next, the transparent conductive film is patterned to form the gateterminal upper connection section 19 g, the source terminal upperconnection section 19 s, and the transfer terminal upper connectionsection 19 p. The gate terminal upper connection section 19 g, thesource terminal upper connection section 19 s, and the transfer terminalupper connection section 19 p are used for protecting the electrodes orwiring lines exposed at each terminal section. In this way, the gateterminal section GT, the source terminal section ST, and the transferterminal section PT are obtained.

Structure of Slot Substrate 201

Next, the structure of the slot substrate 201 will be described ingreater detail.

FIG. 6 is a cross-sectional view schematically illustrating the antennaunit region U and the terminal section IT in the slot substrate 201.

The slot substrate 201 includes the dielectric substrate 51 having afront surface and a rear surface, a third insulating layer 52 formed onthe front surface of the dielectric substrate 51, the slot electrode 55formed on the third insulating layer 52, and a fourth insulating layer58 covering the slot electrode 55. The reflective conductive plate 65 isdisposed opposing the rear surface of the dielectric substrate 51 withthe dielectric layer (air layer) 54 interposed therebetween. The slotelectrode 55 and the reflective conductive plate 65 function as walls ofthe waveguide 301.

In the transmission and/or reception region R1, a plurality of slots 57are formed in the slot electrode 55. The slot 57 is an opening thatopens through the slot electrode 55. In this example, one slot 57 isdisposed in each antenna unit region U.

The fourth insulating layer 58 is formed on the slot electrode 55 andwithin the slot 57. The material of the fourth insulating layer 58 maybe the same as the material of the third insulating layer 52. Bycovering the slot electrode 55 with the fourth insulating layer 58, theslot electrode 55 and the liquid crystal layer LC are not in directcontact with each other, such that the reliability can be enhanced. In acase where the slot electrode 55 is formed of a Cu layer, Cu may eluteinto the liquid crystal layer LC in some cases. In addition, in a casewhere the slot electrode 55 is formed of an Al layer by using a thinfilm deposition technique, the Al layer may include a void. The fourthinsulating layer 58 can prevent the liquid crystal material fromentering the void of the Al layer. Note that in a case where the slotelectrode 55 is formed by bonding an aluminum foil as the Al layer onthe dielectric substrate 51 with an adhesive and patterning it, theproblem of voids can be avoided.

The slot electrode 55 includes a main layer 55M such as a Cu layer or anAl layer. The slot electrode 55 may have a layered structure thatincludes the main layer 55M, as well as an upper layer 55U and a lowerlayer 55L disposed sandwiching the main layer 55M therebetween. Athickness of the main layer 55M may be set in consideration of the skineffect depending on the material, and may be, for example, greater thanor equal to 2 μm and less than or equal to 30 rpm. The thickness of themain layer 55M is typically greater than the thickness of the upperlayer 55U and the lower layer 55L.

In the illustrated example, the main layer 55M is a Cu layer, and theupper layer 55U and the lower layer 55L are Ti layers. By disposing thelower layer 55L between the main layer 55M and the third insulatinglayer 52, the adhesion between the slot electrode 55 and the thirdinsulating layer 52 can be improved. In addition, by providing the upperlayer 55U, corrosion of the main layer 55M (e.g., the Cu layer) can besuppressed.

Since the reflective conductive plate 65 constitutes the wall of thewaveguide 301, it is desirable that the reflective conductive plate 65has a thickness that is three times or greater than the skin depth, andpreferably five times or greater. An aluminum plate, a copper plate, orthe like having a thickness of several millimeters manufactured by acutting out process can be used as the reflective conductive plate 65.

The terminal section IT is provided in the non-transmission and/orreception region R2. The terminal section IT includes the slot electrode55, the fourth insulating layer 58 covering the slot electrode 55, andan upper connection section 60. The fourth insulating layer 58 includesan opening that at least reaches the slot electrode 55. The upperconnection section 60 is in contact with the slot electrode 55 withinthe opening. In the present embodiment, the terminal section IT isdisposed in the seal region Rs, and is connected to the transferterminal section on the TFT substrate (transfer section) by a sealingresin containing conductive particles.

Transfer Section

FIG. 7 is a schematic cross-sectional view for illustrating the transfersection connecting the transfer terminal section PT of the TFT substrate101 and the terminal section IT of the slot substrate 201. In FIG. 7,the same reference numerals are attached to the same components as thosein FIG. 1 to FIG. 4C.

In the transfer section, the upper connection section 60 of the terminalsection IT is electrically connected to the transfer terminal upperconnection section 19 p of the transfer terminal section PT in the TFTsubstrate 101. In the present embodiment, the upper connection section60 and the transfer terminal upper connection section 19 p are connectedwith a resin (sealing resin) 73 (also referred to as a sealing portion73) including conductive beads 71 therebetween.

Each of the upper connection sections 60 and 19 p is a transparentconductive layer such as an ITO film or an IZO film, and there is apossibility that an oxide film is formed on the surface thereof. When anoxide film is formed, the electrical connection between the transparentconductive layers cannot be ensured, and the contact resistance mayincrease. In contrast, in the present embodiment, since thesetransparent conductive layers are bonded with a resin includingconductive beads (for example. Au beads) 71 therebetween, even in a casewhere a surface oxide film is formed, the conductive beads pierce(penetrate) the surface oxide film, allowing an increase in contactresistance to be suppressed. The conductive beads 71 may penetrate notonly the surface oxide film but also penetrate the upper connectionsections 60 and 19 p which are the transparent conductive layers, anddirectly contact the patch connection section 15 p and the slotelectrode 55.

The transfer section may be disposed at both a center portion and aperipheral portion (that is, inside and outside of the donut-shapedtransmission and/or reception region R1 when viewed from the normaldirection of the scanning antenna 1000) of the scanning antenna 1000, oralternatively may be disposed at only one of them. The transfer sectionmay be disposed in the seal region Rs in which the liquid crystals aresealed, or may be disposed outside the seal region Rs (opposite to theliquid crystal layer).

Method of Manufacturing Slot Substrate 201

The slot substrate 201 can be manufactured by the following method, forexample.

First, the third insulating layer (having a thickness of 200 nm, forexample) 52 is formed on the dielectric substrate. A substrate such as aglass substrate or a resin substrate having a high transmittance toelectromagnetic waves (the dielectric constant ε_(M) and the dielectricloss tan δ_(M) are small) can be used as the dielectric substrate. Thedielectric substrate is preferably thin in order to suppress theattenuation of the electromagnetic waves. For example, after forming theconstituent elements such as the slot electrode 55 on the front surfaceof the glass substrate by a process to be described later, the glasssubstrate may be thinned from the rear side. This allows the thicknessof the glass substrate to be reduced to 500 μm or less, for example.

When a resin substrate is used as the dielectric substrate, constituentelements such as TFTs may be formed directly on the resin substrate, ormay be formed on the resin substrate by a transfer method. In a case ofthe transfer method, for example, a resin film (for example, a polymidefilm) is formed on the glass substrate, and after the constituentelements are formed on the resin film by the process to be describedlater, the resin film on which the constituent elements are formed isseparated from the glass substrate. Generally, the dielectric constantε_(M) and the dielectric loss tan δ_(M) of resin are smaller than thoseof glass. The thickness of the resin substrate is, for example, from 3μm to 300 μm. Besides polyimide, for example, a liquid crystal polymercan also be used as the resin material.

The third insulating layer 52 is not particularly limited to a specificfilm, and, for example, a silicon oxide (SiO₂) film, a silicon nitride(SiNx) film, a silicon oxynitride (SiOxNy; x>y) film, a silicon nitrideoxide (SiNxOy; x>y) film, or the like can be used as appropriate.

Next, a metal film is formed on the third insulating layer 52, and thisis patterned to obtain the slot electrode 55 including the plurality ofslots 57. As the metal film, a Cu film (or Al film) having a thicknessof from 2 μm to 5 μm may be used. Here, a layered film obtained bylayering a Ti film, a Cu film, and a Ti film in this order is used.Instead, a layered film may be formed by layering Ti (having a thicknessof 50 nm, for example) and Cu (having a thickness of 5000 nm, forexample) in this order.

Thereafter, the fourth insulating layer (having a thickness of 100 nm or200 nm, for example) 58 is formed on the slot electrode 55 and withinthe slot 57. The material of the fourth insulating layer 58 may be thesame as the material of the third insulating layer. Subsequently, in thenon-transmission and/or reception region R2, an opening that at leastreaches the slot electrode 55 is formed in the fourth insulating layer58.

Next, a transparent conductive film is formed on the fourth insulatinglayer 58 and within the opening of the fourth insulating layer 58, andis patterned to form the upper connection section 60 in contact with theslot electrode 55 within the opening. In this way, the terminal sectionIT is obtained.

Material and Structure of TFT 10

In the present embodiment, a TFT including a semiconductor layer 5 as anactive layer is used as a switching element disposed in each pixel. Thesemiconductor layer 5 is not limited to an amorphous silicon layer, andmay be a polysilicon layer or an oxide semiconductor layer.

In a case where an oxide semiconductor layer is used, the oxidesemiconductor included in the oxide semiconductor layer may be anamorphous oxide semiconductor or a crystalline oxide semiconductorincluding a crystalline portion. Examples of the crystalline oxidesemiconductor include a polycrystalline oxide semiconductor, amicrocrystalline oxide semiconductor, or a crystalline oxidesemiconductor having a c-axis oriented substantially perpendicular tothe layer surface.

The oxide semiconductor layer may have a layered structure of two ormore layers. In cases where the oxide semiconductor layer has a layeredstructure, the oxide semiconductor layer may include an amorphous oxidesemiconductor layer and a crystalline oxide semiconductor layer.Alternatively, the oxide semiconductor layer may include a plurality ofcrystalline oxide semiconductor layers having different crystalstructures. In addition, the oxide semiconductor layer may include aplurality of amorphous oxide semiconductor layers. In cases where theoxide semiconductor layer has a two-layer structure including an upperlayer and a lower layer, the energy gap of the oxide semiconductorincluded in the upper layer is preferably greater than the energy gap ofthe oxide semiconductor included in the lower layer. However, when thedifferent in the energy gap between these layers is relatively small,the energy gap of the lower layer oxide semiconductor may be greaterthan the energy gap of the upper layer oxide semiconductor.

JP 2014-007399 A, for example, describes materials, structures, filmformation methods, and the configuration of oxide semiconductor layershaving layered structures for amorphous oxide semiconductors and each ofthe above described crystalline oxide semiconductors. For reference, theentire contents of JP 2014-007399 A are incorporated herein.

The oxide semiconductor layer may include, for example, at least onemetal element selected from In, Ga, and Zn. In the present embodiment,the oxide semiconductor layer includes, for example, an In—Ga—Zn—O basedsemiconductor (for example, indium gallium zinc oxide). Here, theIn—Ga—Zn—O based semiconductor is a ternary oxide of In (indium), Ga(gallium), and Zn (zinc), and the ratio (composition ratio) of In, Ga,and Zn is not particularly limited to a specific value. For example, theratio includes In:Ga:Zn=2:2:1. In:Ga:Zn=1:1:1, or In:Ga:Zn=1:1:2. Suchan oxide semiconductor layer can be formed from an oxide semiconductorfilm including an In—Ga—Zn—O based semiconductor. Note that a channeletch type TFT having an active layer including an oxide semiconductorsuch as an In—Ga—Zn—O based semiconductor may be referred to as“CE-OS-TFT”.

The In—Ga—Zn—O based semiconductor may be an amorphous semiconductor ora crystalline semiconductor. A crystalline In—Ga—Zn—O basedsemiconductor in which the c-axis is oriented substantiallyperpendicular to the layer surface is preferable as the crystallineIn—Ga—Zn—O based semiconductor.

Note that the crystal structure of the crystalline In—Ga—Zn—O basedsemiconductor is disclosed in, for example, the above-mentioned JP2014-007399 A, JP 2012-134475 A, and JP 2014-209727 A. For reference,the entire contents of JP 2012-134475 A and 2014-209727 A areincorporated herein. Since a TFT including an In—Ga—Zn—O basedsemiconductor layer has high mobility (more than 20 times in comparisonwith a-Si TFTs) and low leakage current (less than 1/100th in comparisonwith a-Si TFTs), such a TFT can suitably be used as a driving TFT (forexample, a TFT included in a driving circuit provided in thenon-transmission and/or reception region) and a TFT provided in eachantenna unit region.

In place of the In—Ga—Zn—O based semiconductor, the oxide semiconductorlayer may include another oxide semiconductor. For example, the oxidesemiconductor layer may include an In—Sn—Zn—O based semiconductor (forexample, In₂O₃—SnO₂—ZnO; InSnZnO). The In—Sn—Zn—O based semiconductor isa ternary oxide of In (indium), Sn (tin), and Zn (zinc). Alternatively,the oxide semiconductor layer may include an In—Al—Zn—O basedsemiconductor, an In—Al—Sn—Zn—O based semiconductor, a Zn—O basedsemiconductor, an In—Zn—O based semiconductor, a Zn—Ti—O basedsemiconductor, a Cd—Ge—O based semiconductor, a Cd—Pb—O basedsemiconductor, CdO (cadmium oxide), a Mg—Zn—O based semiconductor, anIn—Ga—Sn—O based semiconductor, an In—Ga—O based semiconductor, aZr—In—Zn—O based semiconductor, an Hf—In—Zn—O based semiconductor, anAl—Ga—Zn—O based semiconductor, or a Ga—Zn—O based semiconductor.

In the example illustrated in FIG. 3A and FIG. 3B, the TFT 10 is achannel etch type TFT having a bottom gate structure. The channel etchtype TFT does not include an etch stop layer formed on the channelregion, and a lower face of an end portion of each of the source anddrain electrodes, which is closer to the channel, is provided so as tobe in contact with an upper face of the semiconductor layer. The channeletch type TFT is formed by, for example, forming a conductive film for asource/drain electrode on a semiconductor layer and performingsource/drain separation. In the source/drain separation process, thesurface portion of the channel region may be etched.

Note that the TFT 10 may be an etch stop type TFT in which an etch stoplayer is formed on the channel region. In the etch stop type TFT, thelower face of an end portion of each of the source and drain electrodes,which is closer to the channel, is located, for example, on the etchstop layer. The etch stop type TFT is formed as follows; after formingan etch stop layer covering the portion that will become the channelregion in a semiconductor layer, for example, a conductive film for thesource and drain electrodes is formed on the semiconductor layer and theetch stop layer, and source/drain separation is performed.

In addition, although the TFT 10 has a top contact structure in whichthe source and drain electrodes are in contact with the upper face ofthe semiconductor layer, the source and drain electrodes may be disposedto be in contact with the lower face of the semiconductor layer (abottom contact structure). Furthermore, the TFT 10 may have a bottomgate structure having a gate electrode on the dielectric substrate sideof the semiconductor layer, or a top gate structure having a gateelectrode above the semiconductor layer.

Second Embodiment

The scanning antenna of a second embodiment will be described withreference to drawings. The TFT substrate of the scanning antenna of thepresent embodiment differs from the TFT substrate 101 illustrated inFIG. 2A in that a transparent conductive layer that serves as an upperconnection section for each terminal section is provided between thefirst insulating layer and the second insulating layer of the TFTsubstrate.

FIG. 8A to FIG. 8C are cross-sectional views illustrating the gateterminal section GT, the source terminal section ST, and the transferterminal section PT, respectively, of a TFT substrate 102 in the presentembodiment. Constituent elements similar to those in FIG. 4A to FIG. 4Care denoted by the same reference numerals, and the description thereofis omitted. Since the cross-sectional structure of the antenna unitregion U is similar to that of the above-described embodiments (FIG. 3Aand FIG. 3B), the illustration and description thereof will be omitted.

The gate terminal section GT in the present embodiment includes the gatebus line GL formed on a dielectric substrate, the insulating layercovering the gate bus line GL, and the gate terminal upper connectionsection 19 g. The gate terminal upper connection section 19 g is incontact with the gate bus line GL within the contact hole CH2 formed inthe insulating layer. In this example, the insulating layer covering thegate bus line GL includes the gate insulating layer 4 and the firstinsulating layer 11. The second insulating layer 17 is formed on thegate terminal upper connection section 19 g and the first insulatinglayer 11. The second insulating layer 17 includes an opening 18 gexposing a part of the gate terminal upper connection section 19 g. Inthis example, the opening 18 g of the second insulating layer 17 may bedisposed so as to expose the entire contact hole CH2.

The source terminal section ST includes the source bus line SL formed onthe dielectric substrate (here, on the gate insulating layer 4), theinsulating layer covering the source bus line SL, and the sourceterminal upper connection section 19 s. The source terminal upperconnection section 19 s is in contact with the source bus line SL withinthe contact hole CH3 formed in the insulating layer. In this example,the insulating layer covering the source bus line SL includes only thefirst insulating layer 11. The second insulating layer 17 extends overthe source terminal upper connection section 19 s and the firstinsulating layer 11. The second insulating layer 17 includes an opening18 s exposing a part of the source terminal upper connection section 19s. The opening 18 s of the second insulating layer 17 may be disposed soas to expose the entire contact hole CH3.

The transfer terminal section PT includes a source connection wiringline 7 p formed from the same conductive film (source conductive film)as that of the source bus line SL, the first insulating layer 11extending over the source connection wiring line 7 p, and the transferterminal upper connection section 19 p and the patch connection section15 p formed on the first insulating layer 11.

Contact holes CH5 and CH6 are provided in the first insulating layer 11to expose the source connection wiring line 7 p. The transfer terminalupper connection section 19 p is disposed on the first insulating layer11 and within the contact hole CH5, and is in contact with the sourceconnection wiring line 7 p within the contact hole CH5. The patchconnection section 15 p is disposed on the first insulating layer 11 andwithin the contact hole CH6, and is in contact with the sourceconnection wiring line 7 p within the contact hole CH6. The transferterminal upper connection section 19 p is a transparent electrode formedof a transparent conductive film. The patch connection section 15 p isformed of the same conductive film as that of the patch electrode 15.Note that the upper connection sections 19 g, 19 s, and 19 p of therespective terminal sections may be formed of the same transparentconductive film.

The second insulating layer 17 extends over the transfer terminal upperconnection section 19 p, the patch connection section 15 p, and thefirst insulating layer 11. The second insulating layer 17 includes anopening 18 p exposing a part of the transfer terminal upper connectionsection 19 p. In this example, the opening 18 p of the second insulatinglayer 17 is disposed so as to expose the entire contact hole CH5. Incontrast, the patch connection section 15 p is covered with the secondinsulating layer 17.

In this way, in the present embodiment, the source connection wiringline 7 p formed in the source metal layer electrically connects thetransfer terminal upper connection section 19 p of the transfer terminalsection PT and the patch connection section 15 p. Although notillustrated in drawings, similar to the above-described embodiment, thetransfer terminal upper connection section 19 p is connected to the slotelectrode of the slot substrate 201 by a sealing resin containingconductive particles.

In the previously described embodiment, the contact holes CH1 to CH4having different depths are collectively formed after the formation ofthe second insulating layer 17. For example, while the relatively thickinsulating layers (the gate insulating layer 4, the first insulatinglayer 11 and the second insulating layer 17) are etched in the gateterminal section GT, only the second insulating layer 17 is etched inthe transfer terminal section PT. Accordingly, there is a possibilitythat the conductive film (for example, a patch electrode conductivefilm) that serves as the base of the shallow contact holes isconsiderably damaged during etching.

In contrast, in the present embodiment, the contact holes CH1 to CH3,CH5, and CH6 are formed prior to formation of the second insulatinglayer 17. Since these contact holes are formed only in the firstinsulating layer 11 or in the layered film of the first insulating layer11 and the gate insulating layer 4, the difference in depth of thecollectively formed contact holes can be reduced more than in theprevious embodiment. Accordingly, damage to the conductive film thatserves as the base of the contact holes can be reduced. In particular,when an Al film is used for the patch electrode conductive film, since afavorable contact cannot be obtained in a case where the ITO film andthe Al film are brought into direct contact with each other, a cap layersuch as a MoN layer may be formed on the Al film in some cases. In thesecases, there is the advantage that the thickness of the cap layer neednot be increased to compensate for damage during etching.

TFT Substrate 102 Manufacturing Method

The TFT substrate 102 is manufactured by the following method, forexample. FIG. 9 is a diagram illustrating an example of a manufacturingprocess of the TFT substrate 102. Note that in the followingdescription, in cases where the material, thickness, formation method,or the like of each layer are the same as that of the TFT substrate 101described above, the description thereof is omitted.

First, an alignment mark, a base insulating layer, a gate metal layer, agate insulating layer, a semiconductor layer, a contact layer, and asource metal layer are formed on a dielectric substrate in the samemanner as in the TFT substrate 101 to obtain a TFT. In the step offorming the source metal layer, in addition to the source and drainelectrodes and the source bus line, the source connection wiring line 7p is also formed from the source conductive film.

Next, the first insulating layer 11 is formed so as to cover the sourcemetal layer. Subsequently, the first insulating layer 11 and the gateinsulating layer 4 are collectively etched to form the contact holes CH1to CH3, CH5, and CH6. During etching, each of the source bus line SL andthe gate bus line GL functions as an etch stop. In this way, in thetransmission and/or reception region R1, the contact hole CH1 that atleast reaches the drain electrode of the TFT is formed in the firstinsulating layer 11. In addition, in the non-transmission and/orreception region R2, the contact hole CH2 that at least reaches the gatebus line GL is formed in the first insulating layer 11 and the gateinsulating layer 4, and the contact hole CH3 that at least reaches thesource bus line SL and contact holes CH5 and CH6 that at least reach thesource connection wiring line 7 p are formed in the first insulatinglayer 11. The contact hole CH5 may be disposed in the seal region Rs andthe contact hole CH6 may be disposed outside the seal region Rs.Alternatively, both may be disposed outside the seal region Rs.

Next, a transparent conductive film is formed on the first insulatinglayer 11 and within the contact holes CH1 to CH3, CH5, and CH6, andpatterned. In this way, the gate terminal upper connection section 19 gin contact with the gate bus line GL within the contact hole CH2, thesource terminal upper connection section 19 s in contact with the sourcebus line SL within the contact hole CH3, and the transfer terminal upperconnection section 19 p in contact with the source connection wiringline 7 p within the contact hole CH5 are formed.

Next, a patch electrode conductive film is formed on the firstinsulating layer 11, the gate terminal upper connection section 19 g,the source terminal upper connection section 19 s, the transfer terminalupper connection section 19 p, and within the contact holes CH1 and CH6and patterned. In this way, the patch electrode 15 in contact with thedrain electrode 7D within the contact hole CH1 is formed in thetransmission and/or reception region R1, and the patch connectionsection 15 p in contact with the source connection wiring line 7 pwithin the contact hole CH6 is formed in the non-transmission and/orreception region R2. Patterning of the patch electrode conductive filmmay be performed by wet etching. Here, an etchant capable of increasingthe etching selection ratio between the transparent conductive film (ITOor the like) and the patch electrode conductive film (for example, an Alfilm) is used. In this way, when patterning the patch electrodeconductive film, the transparent conductive film can function as an etchstop. Since the portions of the source bus line SL, the gate bus lineGL, and the source connection wiring line 7 p exposed by the contactholes CH2, CH3, and CH5 are covered with an etch stop (transparentconductive film), they are not etched.

Subsequently, the second insulating layer 17 is formed. Thereafter, thesecond insulating layer 17 is patterned by, for example, dry etchingusing a fluorine-based gas. In this way, the opening 18 g exposing thegate terminal upper connection section 19 g, the opening 18 s exposingthe source terminal upper connection section 19 s, and the opening 18 pexposing the transfer terminal upper connection section 19 p areprovided in the second insulating layer 17. In this manner, the TFTsubstrate 102 is obtained.

Third Embodiment

The scanning antenna of a third embodiment will be described withreference to drawings. The TFT substrate in the scanning antenna of thepresent embodiment differs from the TFT substrate 102 illustrated inFIGS. 8A to 8C in that the upper connection section made of atransparent conductive film is not provided in the transfer terminalsection.

FIG. 10A to FIG. 10C are cross-sectional views illustrating the gateterminal section GT, the source terminal section ST, and the transferterminal section PT, respectively, of a TFT substrate 103 in the presentembodiment. Constituent elements similar to those in FIG. 8A to FIG. 8Care denoted by the same reference numerals. Since the structure of theantenna unit region U is similar to that of the above-describedembodiments (FIG. 3A and FIG. 3B), the illustration and descriptionthereof will be omitted.

The structures of the gate terminal section GT and the source terminalsection ST are similar to the structures of the gate terminal sectionand the source terminal section of the TFT substrate 102 illustrated inFIG. 8A and FIG. 8B.

The transfer terminal section PT includes the patch connection section15 p formed on the first insulating layer 11 and a protective conductivelayer 23 layered on the patch connection section 15 p. The secondinsulating layer 17 extends over the protective conductive layer 23 andincludes an opening 18 p exposing a part of the protective conductivelayer 23. In contrast, the patch electrode 15 is covered with the secondinsulating layer 17.

TFT Substrate 103 Manufacturing Method

The TFT substrate 103 is manufactured by the following method, forexample. FIG. 11 is a diagram illustrating an example of a manufacturingprocess of the TFT substrate 103. Note that in the followingdescription, in cases where the material, thickness, formation method,or the like of each layer are the same as that of the TFT substrate 101described above, the description thereof is omitted.

First, an alignment mark, a base insulating layer, a gate metal layer, agate insulating layer, a semiconductor layer, a contact layer, and asource metal layer are formed on a dielectric substrate in the samemanner as in the TFT substrate 101 to obtain a TFT.

Next, the first insulating layer 11 is formed so as to cover the sourcemetal layer. Subsequently, the first insulating layer 11 and the gateinsulating layer 4 are collectively etched to form the contact holes CH1to CH3. During etching, each of the source bus line SL and the gate busline GL functions as an etch stop. In this way, the contact hole CH1that at least reaches the drain electrode of the TFT is formed in thefirst insulating layer 11, the contact hole CH2 that at least reachesthe gate bus line GL is formed in the first insulating layer 11 and thegate insulating layer 4, and the contact hole CH3 that at least reachesthe source bus line SL is formed in the first insulating layer 11. Nocontact hole is formed in the region where the transfer terminal sectionis formed.

Next, a transparent conductive film is formed on the first insulatinglayer 11 and within the contact holes CH1, CH2, and CH3, and patterned.In this way, the gate terminal upper connection section 19 g in contactwith the gate bus line GL within the contact hole CH2 and the sourceterminal upper connection section 19 s in contact with the source busline SL within the contact hole CH3 are formed. In the region where thetransfer terminal section is formed, the transparent conductive film isremoved.

Next, a patch electrode conductive film is formed on the firstinsulating layer 11, on the gate terminal upper connection section 19 gand the source terminal upper connection section 19 s, and within thecontact hole CH1, and patterned. In this way, the patch electrode 15 incontact with the drain electrode 7D within the contact hole CH1 isformed in the transmission and/or reception region R1, and the patchconnection section 15 p is formed in the non-transmission and/orreception region R2. Similar to the previous embodiments, an etchantcapable of ensuring an etching selection ratio between the transparentconductive film (ITO or the like) and the patch electrode conductivefilm is used for patterning the patch electrode conductive film.

Subsequently, the protective conductive layer 23 is formed on the patchconnection section 15 p. A Ti layer, an ITO layer, and an indium zincoxide (IZO) layer (having a thickness of greater than or equal to 50 nmand less than or equal to 100 nm, for example), or the like can be usedas the protective conductive layer 23. Here, a Ti layer (having athickness of 50 nm, for example) is used as the protective conductivelayer 23. Note that the protective conductive layer may be formed on thepatch electrode 15.

Next, the second insulating layer 17 is formed. Thereafter, the secondinsulating layer 17 is patterned by, for example, dry etching using afluorine-based gas. In this way, the opening 18 g exposing the gateterminal upper connection section 19 g, the opening 18 s exposing thesource terminal upper connection section 19 s, and the opening 18 pexposing the protective conductive layer 23 are provided in the secondinsulating layer 17. In this manner, the TFT substrate 103 is obtained.

Structure of Slot Substrate 203

FIG. 12 is a schematic cross-sectional view for illustrating a transfersection that connects the transfer terminal section PT of the TFTsubstrate 103 and a terminal section IT of a slot substrate 203 in thepresent embodiment. In FIG. 12, the same reference numerals are attachedto the same constituent elements as those in the embodiments describedabove.

First, the slot substrate 203 in this embodiment will be described. Theslot substrate 203 includes the dielectric substrate 51, the thirdinsulating layer 52 formed on the front surface of the dielectricsubstrate 51, the slot electrode 55 formed on the third insulating layer52, and the fourth insulating layer 58 covering the slot electrode 55.The reflective conductive plate 65 is disposed opposing the rear surfaceof the dielectric substrate 51 with the dielectric layer (air layer) 54interposed therebetween. The slot electrode 55 and the reflectiveconductive plate 65 function as walls of the waveguide 301.

The slot electrode 55 has a layered structure in which a Cu layer or anAl layer is the main layer 55M. In the transmission and/or receptionregion R1, a plurality of slots 57 are formed in the slot electrode 55.The structure of the slot electrode 55 in the transmission and/orreception region R1 is the same as the structure of the slot substrate201 described above with reference to FIG. 6.

The terminal section IT is provided in the non-transmission and/orreception region R2. The terminal section IT includes an openingexposing the front surface of the slot electrode 55 provided in thefourth insulating layer 58. The exposed area of the slot electrode 55serves as a contact surface 55 c. As described above, in the presentembodiment, the contact surface 55 c of the slot electrode 55 is notcovered with the fourth insulating layer 58.

In the transfer section, the protective conductive layer 23 covering thepatch connection section 15 p of the TFT substrate 103 and the contactsurface 55 c of the slot electrode 55 of the slot substrate 203 areconnected with a resin (sealing resin) containing the conductive beads71 therebetween.

As in the above-described embodiments, the transfer section in thepresent embodiment may be disposed at both the central portion and theperipheral portion of the scanning antenna, or may be disposed in onlyone of them. In addition, the transfer section may be disposed withinthe seal region Rs or may be disposed outside the seal region Rs(opposite to the liquid crystal layer).

In the present embodiment, no transparent conductive film is provided onthe transfer terminal PT and the contact surface of the terminal sectionIT. Accordingly, the protective conductive layer 23 and the slotelectrode 55 of the slot substrate 203 can be connected with a sealingresin containing conductive particles therebetween.

Furthermore, in the present embodiment, since the difference in thedepth of the collectively formed contact holes is small in comparisonwith the first embodiment (FIG. 3A to FIG. 4C), the damage to theconductive film that serves as the base of the contact holes can bereduced.

Slot Substrate 203 Manufacturing Method

The slot substrate 203 is manufactured as follows. Since the material,the thickness, and the formation method of each layer are the same asthose of the slot substrate 201, the description thereof is omitted.

First, the third insulating layer 52 and the slot electrode 55 areformed on the dielectric substrate in the same manner as the slotsubstrate 201, and a plurality of slots 57 are formed in the slotelectrode 55. Next, the fourth insulating layer 58 is formed on the slotelectrode 55 and within the slot. Subsequently, the opening 18 p isformed in the fourth insulating layer 58 so as to expose a region thatwill become the contact surface of the slot electrode 55. In this way,the slot substrate 203 is manufactured.

Internal Heater Structure

As described above, it is preferable that the dielectric anisotropyΔε_(M) of the liquid crystal material used for the antenna unit of theantenna be large. However, the viscosity of liquid crystal materials(nematic liquid crystals) having large dielectric anisotropies Δε_(M) ishigh, and the slow response speed may lead to problems. In particular,as the temperature decreases, the viscosity increases. The environmentaltemperature of a scanning antenna mounted on a moving body (for example,a ship, an aircraft, or an automobile) fluctuates. Accordingly, it ispreferable that the temperature of the liquid crystal material can beadjusted to a certain extent, for example 30° C. or higher, or 45′C orhigher. The set temperature is preferably set such that the viscosity ofthe nematic liquid crystal material is about 10 cP (centipoise) or less.

In addition to the above structure, the scanning antenna according tothe embodiments of the disclosure preferably has an internal heaterstructure. A resistance heating type heater that uses Joule heat ispreferable as the internal heater. The material of the resistive filmfor the heater is not particularly limited to a specific material, but aconductive material having relatively high specific resistance such asITO or IZO can be utilized, for example. In addition, to adjust theresistance value, a resistive film may be formed with thin lines ormeshes made of a metal (e.g., nichrome, titanium, chromium, platinum,nickel, aluminum, and copper). Thin lines or meshes made of ITO and IZOmay be also used. The resistance value may be set according to therequired calorific value.

For example, to set the heat generation temperature of the resistivefilm to 30° C. for an area (roughly 90000 mm²) of a circle having adiameter of 340 mm with 100 V AC (60 Hz), the resistance value of theresistive film should be set to 139Ω, the current should be set to 0.7A, and the power density should be set to 800 W/m². To set the heatgeneration temperature of the resistive film to 45° C. for the same areawith 100 V AC (60 Hz), the resistance value of the resistive film shouldbe set to 82Ω, the current should be set to 1.2 A, and the power densityshould be set to 1350 W/m².

The resistive film for the heater may be provided anywhere as long as itdoes not affect the operation of the scanning antenna, but toefficiently heat the liquid crystal material, the resistive film ispreferably provided near the liquid crystal layer. For example, asillustrated in a TFT substrate 104 illustrated in FIG. 13A, a resistivefilm 68 may be formed on almost the entire surface of the dielectricsubstrate 1. FIG. 13A is a schematic plan view of the TFT substrate 104including the heater resistive film 68. The resistive film 68 is coveredwith, for example, the base insulating film 2 illustrated in FIG. 3A.The base insulating film 2 is formed to have a sufficient dielectricstrength.

The resistive film 68 preferably has openings 68 a, 68 b, and 68 c. Whenthe TFT substrate 104 and the slot substrate are bonded to each other,the slots 57 are positioned to oppose the patch electrodes 15. At thistime, the opening 68 a is disposed such that the resistive film 68 isnot present within an area having a distance d from an edge of the slot57. The distance d is 0.5 mm, for example. In addition, it is alsopreferable to dispose the opening 68 b under the auxiliary capacitanceCS and to dispose the opening 68 c under the TFT.

Note that the size of the antenna unit U is, for example, 4 mm×4 mm. Inaddition, as illustrated in FIG. 13B, a width s2 of the slot 57 is 0.5mm, a length s1 of the slot 57 is 3.3 mm, a width p2 of the patchelectrode 15 in a width direction of the slot 57 is 0.7 mm, and a widthp1 of the patch electrode 15 in the length direction of the slot 57 is0.5 mm. Note that the size, shape, arrangement relationships, and thelike of the antenna unit U, the slot 57, and the patch electrode 15 arenot limited to the examples illustrated in FIG. 13A and FIG. 13B.

To further reduce the influence of the electric field from the heaterresistive film 68, a shield conductive layer may be formed. The shieldconductive layer is formed, for example, on the base insulating film 2over almost the entire surface of the dielectric substrate 1. While theshield conductive layer need not include the openings 68 a and 68 b likein the resistive film 68, the opening 68 c is preferably providedtherein. The shield conductive layer is formed of, for example, analuminum layer, and is set to ground potential.

In addition, the resistive film preferably has a distribution of theresistance value so that the liquid crystal layer can be uniformlyheated. The temperature distribution of the liquid crystal layer ispreferably such that difference between the maximum temperature and theminimum temperature (temperature fluctuation) is, for example, less thanor equal to 15° C. When the temperature fluctuation exceeds 15° C.,there are cases that the phase difference modulation varies within theplane, and good quality beam formation cannot be achieved. Furthermore,when the temperature of the liquid crystal layer approaches the Tnipoint (for example, 125° C.), Δε_(M) becomes small, which is notpreferable.

With reference to FIG. 14A, FIG. 14B, and FIG. 15A to FIG. 15C, thedistribution of the resistance value in the resistive film will bedescribed. FIG. 14A. FIG. 14B, and FIG. 15A to FIG. 15C illustrateschematic structures of resistance heating structures 80 a to 80 e and acurrent distribution. The resistance heating structure includes aresistive film and a heater terminal.

The resistance heating structure 80 a illustrated in FIG. 14A includes afirst terminal 82 a, a second terminal 84 a, and a resistive film 86 aconnected thereto. The first terminal 82 a is disposed at the center ofthe circle, and the second terminal 84 a is disposed along the entirecircumference. Here, the circle corresponds to the transmission and/orreception region R1. When a DC voltage is applied between the firstterminal 82 a and the second terminal 84 a, for example, a current IAflows radially from the first terminal 82 a to the second terminal 84 a.Accordingly, even though an in-plane resistance value is constant, theresistive film 86 a can uniformly generate heat. Of course, thedirection of a current flow may be a direction from the second terminal84 a to the first terminal 82 a.

The resistance heating structure 80 b illustrated in FIG. 14B includes afirst terminal 82 b, a second terminal 84 b, and a resistive film 86 bconnected thereto. The first terminal 82 b and the second terminal 84 bare disposed adjacent to each other along the circumference. Aresistance value of the resistive film 86 b has an in-plane distributionsuch that an amount of heat generated per unit area by the current IAflowing between the first terminal 82 b and the second terminal 84 b inthe resistive film 86 b is constant. In a case where the resistive film86 b is formed of a thin line, for example, the in-plane distribution ofthe resistance value of the resistive film 86 may be adjusted by thethickness of the thin line and the density of the thin line.

The resistance heating structure 80 c illustrated in FIG. 15A includes afirst terminal 82 c, a second terminal 84 c, and a resistive film 86 cconnected thereto. The first terminal 82 c is disposed along thecircumference of the upper half of the circle, and the second terminal84 c is disposed along the circumference of the lower half of thecircle. When the resistive film 86 c is constituted by thin linesextending vertically between the first terminal 82 c and the secondterminal 84 c, for example, a thickness and a density of the thin linesnear the center are adjusted such that the amount of heat generated perunit area by the current IA is constant in the plane.

The resistance heating structure 80 d illustrated in FIG. 15B includes afirst terminal 82 d, a second terminal 84 d, and a resistive film 86 dconnected thereto. The first terminal 82 d and the second terminal 84 dare provided so as to extend in the vertical direction and thehorizontal direction, respectively, along the diameter of the circle.Although simplified in drawings, the first terminal 82 d and the secondterminal 84 d are electrically insulated from each other.

In addition, the resistance heating structure 80 e illustrated in FIG.15C includes a first terminal 82 e, a second terminal 84 e, and aresistive film 86 e connected thereto. Unlike the resistance heatingstructure 80 d, both the first terminal 82 e and the second terminal 84e of the resistance heating structure 80 e include four portionsextending from the center of the circle in four directions upward,downward, left, and right. The portions of the first terminal 82 e andthe second terminal 84 e that form a 90 degree angle with each other aredisposed such that the current IA flows clockwise.

In both of the resistance heating structure 80 d and the resistanceheating structure 80 e, the thin line closer to the circumference isadjusted to be thick and have a higher density, for example, so that thecloser to the circumference the more the current IA increases and theamount of heat generated per unit area becomes uniform within the plane.

Such an internal heater structure may automatically operate, forexample, when it is detected that the temperature of the scanningantenna has fallen below a preset temperature. Of course, it may alsooperate in response to the operation of a user.

External Heater Structure

Instead of the internal heater structure described above, or in additionto the internal heater structure, the scanning antenna according to theembodiments of the disclosure may include an external heater structure.A resistance heating type heater that uses Joule heat is preferable asthe external heater although various known heaters can be used. Assumethat a part generating heat in the heater is a heater section. In thefollowing description, an example in which a resistive film is used asthe heater section is described. In the following description also, theresistive film is denoted by the reference numeral 68.

For example, the heater resistive film 68 is preferably disposed as in aliquid crystal panel 100Pa or 100Pb illustrated in FIGS. 16A and 16B.Here, the liquid crystal panels 100Pa and 100Pb includes the TFTsubstrate 101, the slot substrate 201, and the liquid crystal layer LCprovided therebetween in the scanning antenna 1000 illustrated in FIG.1, and further includes a resistance heating structure including theresistive film 68 on an outer side of the TFT substrate 101. Theresistive film 68 may be formed on a side of the dielectric substrate 1of the TFT substrate 101 closer to the liquid crystal layer LC. However,such a configuration complicates a manufacturing process of the TFTsubstrate 101, and thus the resistive film 68 is preferably disposed onthe outer side of the TFT substrate 101 (opposite to the liquid crystallayer LC).

The liquid crystal panel 100Pa illustrated in FIG. 16A includes theheater resistive film 68 formed on an outer surface of the dielectricsubstrate 1 of the TFT substrate 101 and a protection layer 69 acovering the heater resistive film 68. The protection layer 69 a may beomitted. The scanning antenna is housed in a case made of plastic, forexample, and therefore, the resistive film 68 is not directly contactedby the user.

The resistive film 68 can be formed on the outer surface of thedielectric substrate 1 by use of, for example, a known thin filmdeposition technique (e.g., sputtering, CVD), a coating method, or aprinting method. The resistive film 68 is patterned as needed.Patterning is performed through a photolithographic process, forexample.

The material of the heater resistive film 68 is not particularly limitedto a specific material as described above for the internal heaterstructure, but a conductive material having relatively high specificresistance such as ITO or IZO can be utilized, for example. In addition,to adjust the resistance value, the resistive film 68 may be formed withthin lines or meshes made of a metal (e.g., nichrome, titanium,chromium, platinum, nickel, aluminum, and copper). Thin lines or meshesmade of ITO and IZO may be also used. The resistance value may be setaccording to the required calorific value.

The protection layer 69 a is made of an insulating material and formedto cover the resistive film 68. The protection layer 69 a may not beformed on a portion where the resistive film 68 is patterned and thedielectric substrate 1 is exposed. The resistive film 68 is patterned soas not to decrease the antenna performance as described later. In a casewhere a presence of the material forming the protection layer 69 acauses the antenna performance to decrease, the patterned protectionlayer 69 a is preferably used similar to the resistive film 68.

The protection layer 69 a may be formed by any of a wet process and adry process. For example, a liquid curable resin (or precursor of resin)or a solution is applied on the surface of the dielectric substrate 1 onwhich the resistive film 68 is formed, and thereafter, the curable resinis cured to form the protection layer 69 a. The liquid resin or theresin solution is applied to the surface of the dielectric substrate 1to have a predetermined thickness by various coating methods (e.g.,using a slot coater, a spin coater, a spray) or various printingmethods. After that, the resultant substrate is subjected to roomtemperature curing, thermal curing, or light curing depending on a kindof the resin to form the protection layer 69 a which is an insulatingresin film. The insulating resin film may be patterned by aphotolithographic process, for example.

A curable resin material is preferably used as a material for formingthe protection layer 69 a. The curable resin material includes a thermalcuring type resin material and a light curing type resin material. Thethermal curing type includes a thermal cross-linking type and a thermalpolymerization type.

Examples of the resin material of thermal cross-linking type include acombination of an epoxy-based compound (e.g., an epoxy resin) andamine-based compound, a combination of an epoxy-based compound and ahydrazide-based compound, a combination of an epoxy-based compound andan alcohol-based compound (e.g., including a phenol resin), acombination of an epoxy-based compound and a carboxylic acid-basedcompound (e.g., including an acid anhydride), a combination of anisocyanate-based compound and an amine-based compound, a combination ofan isocyanate-based compound and a hydrazide-based compound, acombination of an isocyanate-based compound and an alcohol-basedcompound (e.g., including an urethane resin), and a combination of anisocyanate-based compound and a carboxylic acid-based compound. Examplesof a cationic polymerization type adhesive include a combination of anepoxy-based compound and a cationic polymerization initiator (arepresentative cationic polymerization initiator: aromatic sulfoniumsalt). Examples of the resin material of radical polymerization typeinclude a combination of a monomer and/or an oligomer containing a vinylgroup of various acrylic, methacrylic, and urethane modified acrylic(methacrylic) resins and a radical polymerization initiator (arepresentative radical polymerization initiator: azo-based compound(e.g., azobisisobutyronitrile (AIBN))), and examples of the resinmaterial of ring-opening polymerization type include an ethyleneoxide-based compound, an ethyleneimine-based compound, and asiloxane-based compound. In addition, examples of the resin material mayalso include a maleimide resin, a combination of a maleimide resin andan amine, a combination of maleimide and a methacrylic compound, abismaleimide-triazine resin, and a polyphenylene ether resin. Moreover,polyimide can be preferably used. Note that “polyimide” includingpolyamic acid that is a precursor of polyimide is used. Polyimide isused in combination with an epoxy-based compound or an isocyanate-basedcompound, for example.

In terms of heat resistance, chemical stability, and mechanicalcharacteristics, the thermal curing type resin material is preferablyused. Particularly, the resin material containing an epoxy resin or apolyimide resin is preferable, and in terms of the mechanicalcharacteristics (in particular, mechanical strength) and hygroscopicity,the resin material containing a polyimide resin is preferable. Apolyimide resin and an epoxy resin may be mixed to be used. A polyimideresin and/or an epoxy resin may be mixed with a thermoplastic resinand/or an elastomer. Furthermore, rubber-modified polyimide resin and/orepoxy resin may be mixed. A thermoplastic resin or an elastomer can bemixed to improve flexibility or toughness. Even when the rubber-modifiedresin is used, the same effect can be obtained.

A cross-linking reaction and/or a polymerization reaction of the lightcuring type material is caused by ultraviolet light or visible light,and the light curing type material cures. The light curing type includesa radical polymerization type and a cationic polymerization type, forexample. Representative examples of the radical polymerization typematerial include a combination of an acrylic resin (epoxy modifiedacrylic resin, urethane modified acrylic resin, silicone modifiedacrylic resin) and a photopolymerization initiator. Examples of anultraviolet radical polymerization initiator include an acetophenonetype initiator and a benzophenone type initiator. Examples of a visiblelight radical polymerization initiator include a benzylic type initiatorand a thioxanthone type initiator. A combination of an epoxy compoundand a photo cationic polymerization initiator is a representativeexample of the cationic polymerization type. Examples of a photocationic polymerization initiator include an iodonium salt-basedcompound. A resin material having both light curing and thermal curingcharacteristics can be used also.

The liquid crystal panel 100Pb illustrated in FIG. 16B is different fromthe liquid crystal panel 100Pa in that the liquid crystal panel 100Pbfurther includes an adhesive layer 67 between the resistive film 68 andthe dielectric substrate 1. Moreover, the liquid crystal panel 100Pb isdifferent from the liquid crystal panel 100Pa in that the protectionlayer 69 b is formed using a polymer film or glass plate fabricated inadvance.

For example, the liquid crystal panel 100Pb including the protectionlayer 69 b formed of a polymer film is manufactured as below.

First, an insulating polymer film that will become the protection layer69 b is prepared. Examples of a polymer film include a polyester filmmade of polyethylene terephthalate, polyethylene naphthalate or thelike, and a film made of super engineering plastic such as polyphenylenesulfone, polyimide, or polyamide. A thickness of the polymer film (thatis, a thickness of the protection layer 69 b) is greater than or equalto 5 μm and less than or equal to 200 μm, for example.

The resistive film 68 is formed on one surface of this polymer film. Theresistive film 68 can be formed by the above method. The resistive film68 may be patterned, and the polymer film may be also patterned asneeded.

The polymer film on which the resistive film 68 is formed (that is, amember integrally formed of the protection layer 69 b and the resistivefilm 68) is bonded to the dielectric substrate 1 with an adhesive.Examples of the adhesive include the same curable resin as the curableresin used to form the protection layer 69 a described above.Furthermore, a hot-melt type resin material (adhesive) can be used. Thehot-melt type resin material contains a thermoplastic resin as a maincomponent, and melts by heating and solidifies by cooling. Examples ofthe hot-melt type resin material include polyolefin-based (e.g.,polyethylene, polypropylene), polyamide-based, and ethylene vinylacetate-based resins. A reactive urethane-based hot-melt resin material(adhesive) is also available. In terms of adhesive and durability, thereactive urethane-based resin is preferable.

The adhesive layer 67 may be patterned similar to the resistive film 68and the protection layer (polymer film) 69 b. However, the adhesivelayer 67 needs only fix the resistive film 68 and the protection layer69 b to the dielectric substrate 1, and may be smaller than theresistive film 68 and the protection layer 69 b.

In place of the polymer film, the glass plate may be also used to formthe protection layer 69 b. A manufacturing process may be the same asthe case using the polymer film. A thickness of the glass plate ispreferably less than or equal to 1 mm and further preferably less thanor equal to 0.7 mm. A lower limit of the thickness of the glass plate isnot specifically specified, but in terms of handling, the thickness ofthe glass plate is preferably greater than or equal to 0.3 mm.

In the liquid crystal panel 100Pb illustrated in FIG. 16B, the resistivefilm 68 formed on the protection layer (polymer film or glass plate) 69b is fixed to the dielectric substrate 1 via the adhesive layer 67, butthe resistive film 68 needs only be disposed in contact with thedielectric substrate 1, and the resistive film 68 and the protectionlayer 69 b are not necessarily fixed (bonded) to the dielectricsubstrate 1. In other words, the adhesive layer 67 may be omitted. Forexample, the polymer film on which the resistive film 68 is formed (thatis, a member integrally formed of the protection layer 69 b and theresistive film 68) may be disposed such that the resistive film 68 isbrought into contact with the dielectric substrate 1 and is pressedagainst the dielectric substrate 1 with the case housing the scanningantenna. For example, since the thermal contact resistance possiblyincreases when the polymer film on which the resistive film 68 is formedis merely disposed only, the polymer film is preferably pressed againstthe dielectric substrate to decrease the thermal contact resistance.Using such a configuration allows the member integrally formed of theresistive film 68 and the protection layer (polymer film or glass plate)69 b to be detachable.

Note that in a case where the resistive film 68 (and the protectionlayer 69 b) is patterned as described later, the resistive film 68 (andthe protection layer 69 b) is preferably fixed to the dielectricsubstrate 1 to a degree not to shift in a position with respect to theTFT substrate so that the antenna performance does not decrease.

The heater resistive film 68 may be provided anywhere as long as it doesnot affect the operation of the scanning antenna, but to efficientlyheat the liquid crystal material, the resistive film is preferablyprovided near the liquid crystal layer. Therefore, the heater resistivefilm 68 is preferably provided on the outer side of the TFT substrate101 as illustrated in FIGS. 16A and 16B. In addition, the resistive film68 directly provided on the outer side of the dielectric substrate 1 ofthe TFT substrate 101 as illustrated in FIG. 16A is preferable, becausean energy efficiency is higher, and controllability of the temperatureis higher than those in a case in which the resistive film 68 isprovided on the outer side of the dielectric substrate 1 with theadhesive layer 67 therebetween as illustrated in FIG. 16B.

For example, the resistive film 68 may be formed on almost the entiresurface of the dielectric substrate 1 of the TFT substrate 104illustrated in FIG. 13A. The resistive film 68 preferably includes theopenings 68 a, 68 b, and 68 c as described for the internal heaterstructure.

The protection layers 69 a and 69 b may be formed on the entire surfaceto cover the resistive film 68. As described above, in a case where theprotection layer 69 a or 69 b has an adverse effect on antennacharacteristics, openings corresponding to the openings 68 a, 68 b, and68 c of the resistive film 68 may be provided. In this case, theopenings of the protection layer 69 a or 69 b are formed inside theopenings 68 a, 68 b, and 68 c of the resistive film 68.

To further reduce the influence of the electric field from the heaterresistive film 68, a shield conductive layer may be formed. The shieldconductive layer is formed on the side of the resistive film 68 closerto the dielectric substrate 1 with an insulating film therebetween, forexample. The shield conductive layer is formed on almost the entiresurface of the dielectric substrate 1. While the shield conductive layerneed not include the openings 68 a and 68 b like in the resistive film68, the opening 68 c is preferably provided therein. The shieldconductive layer is formed of, for example, an aluminum layer, and isset to ground potential. In addition, the resistive film preferably hasa distribution of the resistance value so that the liquid crystal layercan be uniformly heated. These structures are similar to the structuresof the internal heater structure described above.

The resistive film needs only heat the liquid crystal layer LC in thetransmission and/or reception region R1, and may be provided on an areacorresponding to the transmission and/or reception region R1 as anexample described above. However, the structure of the resistive film isnot limited to this structure. For example, as illustrated in FIG. 2A,in a case where the TFT substrate 101 has an outline capable of defininga rectangular area encompassing the transmission and/or reception regionR1, the resistive film may be provided on an area corresponding to therectangular area encompassing the transmission and/or reception regionR1. Of course, the outline of the resistive film is not limited to arectangle, and may be any shape encompassing the transmission and/orreception region R1.

In the above example, the resistive film is disposed on the outer sideof the TFT substrate 101, but the resistive film may be disposed on anouter side of the slot substrate 201 (opposite to the liquid crystallayer LC). In this case also, the resistive film may be formed directlyon the dielectric substrate 51 similar to the liquid crystal panel 100Pain FIG. 16A, or the resistive film formed on the protection layer(polymer film or glass plate) with the adhesive layer therebetween maybe fixed to the dielectric substrate 51 similar to the liquid crystalpanel 100Pb in FIG. 16B. Alternatively, the protection layer on whichthe resistive film is formed without the adhesive layer (that is, themember integrally formed of the protection layer and the resistive film)may be disposed such that the resistive film is in contact with thedielectric substrate 51. For example, since the thermal contactresistance possibly increases in a case where the polymer film on whichthe resistive film is formed is merely disposed only, the polymer filmis preferably pressed against the dielectric substrate 51 to decreasethe thermal contact resistance. Using such a configuration allows themember integrally formed of the resistive film and the protection layer(polymer film or glass plate) to be detachable. Note that in a casewhere the resistive film (and the protection layer) is patterned, theresistive film (and the protection layer) is preferably fixed to thedielectric substrate to a degree not to shift in a position with respectto the slot substrate so that the antenna performance does not decrease.

In a case where the resistive film is disposed on the outer side of theslot substrate 201, openings are preferably provided in the resistivefilm at positions corresponding to the slots 57. The resistive film haspreferably a thickness enough to transmit microwaves.

Here, the example in which the resistive film is used as the heatersection is described, but other than the example, a nichrome line (e.g.,winding wire), an infrared light heater section, and the like may beused as the heater section, for example. In the cases like these also,the heater section is preferably disposed not to decrease the antennaperformance.

Such an external heater structure may automatically operate, forexample, when it is detected that the temperature of the scanningantenna has fallen below a preset temperature. Of course, it may alsooperate in response to the operation of a user.

As a temperature control device for making the external heater structureautomatically operate, various known thermostats can be used, forexample. For example, a thermostat using bimetal may be connectedbetween one of two terminals connected with the resistive film and apower source. Of course, a temperature control device may be used whichsupplies current to the external heater structure from the power sourceto prevent the temperature from falling below a preset temperature byuse of a temperature sensor.

Driving Method

Since an antenna unit array of the scanning antenna according to theembodiments of the disclosure has a structure similar to that of an LCDpanel, line sequential driving is performed in the same manner as an LCDpanel. However, in a case where existing driving methods for LCD panelsare applied, the following problems may occur. Problems that may occurin the scanning antenna will be described with reference to theequivalent circuit diagram of one antenna unit of the scanning antennaillustrated in FIG. 17.

First, as mentioned above, since the specific resistance of liquidcrystal materials having large dielectric anisotropies Δε_(M)(birefringence Δn with respect to visible light) in the microwave rangeis low, in a case where driving methods for LCD panels are applied asis, the voltage applied to the liquid crystal layer cannot besufficiently maintained. Then, the effective voltage applied to theliquid crystal layer decreases, and the electrostatic capacitance valueof the liquid crystal capacitance does not reach the target value.

In this way, when the voltage applied to the liquid crystal layerdeviates from the predetermined value, the direction in which the gainof the antenna becomes maximum deviates from the intended direction.Then, for example, communication satellites cannot be accuratelytracked. To prevent this, an auxiliary capacitance CS is providedelectrically in parallel with the liquid crystal capacitance Clc, andthe capacitance value C-Ccs of the auxiliary capacitance CS issufficiently increased. It is desirable that the capacitance value C-Ccsof the auxiliary capacitance CS is appropriately set, so that thevoltage holding rate of the liquid crystal capacitance Clc may be, forexample, at least 30%, and preferably 55% or more. The capacitance valueC-Ccs of the auxiliary capacitance CS depends on the area of electrodesCSE1 and CSE2, and the thickness and the dielectric constant of thedielectric layer between the electrode CSE1 and the electrode CSE2.Typically, the same voltage as that of the patch electrode 15 issupplied to the electrode CSE1, and the same voltage as that of the slotelectrode 55 is supplied to the electrode CSE2.

In addition, when a liquid crystal material having a low specificresistance is utilized, a voltage drop due to the interface polarizationand/or the orientation polarization also occurs. To prevent the voltagedrop due to these polarizations, it is conceivable to apply asufficiently high voltage in anticipation of the voltage drop. However,when a high voltage is applied to a liquid crystal layer having a lowspecific resistance, a dynamic scattering effect (DS effect) may occur.The DS effect is caused by the convection of ionic impurities in theliquid crystal layer, and the dielectric constant ε_(M) of the liquidcrystal layer approaches the average value ((ε_(M)//+2ε_(M)⊥)/3). Also,to control the dielectric constant ε_(M) of the liquid crystal layer inmultiple stages (multiple gray scales), it is not always possible toapply a sufficiently high voltage.

To suppress the above-described DS effect and/or the voltage drop due tothe polarization, the polarity inversion period of the voltage appliedto the liquid crystal layer may be sufficiently shortened. As is wellknown, in a case where the polarity inversion period of the appliedvoltage is shortened, a threshold voltage at which the DS effect occursbecomes higher. Accordingly, the polarity inversion frequency may bedetermined such that the maximum value of the voltage (absolute value)applied to the liquid crystal layer is less than the threshold voltageat which the DS effect occurs. For the polarity inversion frequency of300 Hz or greater, even in a case where a voltage with an absolute valueof 10 V is applied to a liquid crystal layer having a specificresistance of 1×10¹⁰ Ω·cm and a dielectric anisotropy Δε (@1 kHz) ofabout −0.6, a good quality operation can be ensured. In addition, in acase where the polarity inversion frequency (typically equal to twicethe frame frequency) is 300 Hz or greater, the voltage drop caused bythe polarization is also suppressed. From the viewpoint of powerconsumption and the like, the upper limit of the polarity inversionperiod is preferably about less than or equal to 5 KHz.

The polarity inversion frequency of the voltage applied to the liquidcrystal layer naturally depends on the liquid crystal material(particularly the specific resistance). Accordingly, depending on theliquid crystal material, even in a case where a voltage with a polarityinversion period of less than 300 Hz is applied, the above describedproblem does not arise. However, since the liquid crystal material usedfor the scanning antenna according to the embodiments of the disclosurehas a lower specific resistance than that of the liquid crystal materialused for LCDs, it is preferable for the liquid crystal layer to bedriven at roughly 60 Hz or greater.

As described above, since the viscosity of the liquid crystal materialdepends on the temperature, it is preferable that the temperature of theliquid crystal layer be appropriately controlled. The physicalproperties and driving conditions of the liquid crystal materialdescribed here are values under the operating temperature of the liquidcrystal layer. Conversely, the temperature of the liquid crystal layeris preferably controlled such that it can be driven under the aboveconditions.

An example of a waveform of a signal used for driving the scanningantenna will be described with reference to FIG. 18A to FIG. 18G. Notethat FIG. 18D illustrates the waveform of the display signal Vs (LCD)supplied to the source bus line of the LCD panel for comparison.

FIG. 18A illustrates the waveform of a scanning signal Vg supplied to agate bus line G-L1, FIG. 18B illustrates the waveform of a scanningsignal Vg supplied to a gate bus line G-L2, FIG. 18C illustrates thewaveform of a scanning signal Vg supplied to a gate bus line G-L3, FIG.18E illustrates the waveform of a data signal Vda supplied to the sourcebus line, FIG. 18F illustrates the waveform of a slot voltage Vidcsupplied to the slot electrode of the slot substrate (slot electrode),and FIG. 18G illustrates the waveform of the voltage applied to theliquid crystal layer of each antenna unit.

As illustrated in FIG. 18A to FIG. 18C, the voltage of the scanningsignal Vg supplied to the gate bus line sequentially changes from a lowlevel (VgL) to a high level (VgH). VgL and VgH can be appropriately setaccording to the characteristics of the TFT. For example, VgL=from −5 Vto 0 V, and VgH=+20 V. Also, VgL=−20 V and VgH=+20 V are possible. Aperiod from the time when the voltage of the scanning signal Vg of aparticular gate bus line switches from the low level (VgL) to the highlevel (VgH) until the time when the voltage of the next gate bus lineswitches from VgL to VgH will be referred to as one horizontal scanperiod (1H). In addition, the period during which the voltage of eachgate bus line is at the high level (VgH) will be referred to as aselection period PS. In this selection period PS, the TFTs connected tothe respective gate bus lines are turned on, and the current voltage ofthe data signal Vda supplied to the source bus line is supplied to thecorresponding patch electrode. The data signal Vda is, for example, from−15 V to 15 V (an absolute value is 15 V), and, for example, a datasignal Vda having different absolute values corresponding to 12 grayscales, or preferably corresponding to 16 gray scales is used.

Here, a case is exemplified where an intermediate voltage is applied toall antenna units. That is, it is assumed that the voltage of the datasignal Vda is constant with respect to all antenna units (assumed to beconnected to m gate bus lines). This corresponds to the case where thegray levels are displayed on the LCD panel over the whole surfacethereof. At this time, dot inversion driving is performed in the LCDpanel. That is, in each frame, the display signal voltage is suppliedsuch that the polarities of adjacent pixels (dots) are opposite to eachother.

FIG. 18D illustrates the waveform of the display signal of the LCD panelon which the dot inversion driving is performed. As illustrated in FIG.18D, the polarity of Vs (LCD) is inverted every 1H. The polarity of theVs (LCD) supplied to a source bus line adjacent to a source bus linesupplied with the Vs (LCD) having this waveform is opposite to thepolarity of the Vs (LCD) illustrated in FIG. 18D. Furthermore, thepolarity of the display signal supplied to all the pixels is invertedfor each frame. In the LCD panels, it is difficult to perfectly matchthe magnitude of the effective voltage applied to the liquid crystallayer between the positive polarity and the negative polarity, andfurther, the difference in effective voltage becomes a difference inluminance, which is observed as flicker. To make this flicker lessnoticeable, the pixels (dots) to which voltages of different polaritiesare applied are spatially dispersed in each frame. Typically, byperforming the dot inversion driving, the pixels (dots) having differentpolarities are arranged in a checkered pattern.

In contrast, in the scanning antenna, the flicker itself is notproblematic. That is, it is sufficient for the electrostatic capacitancevalue of the liquid crystal capacitance to be an intended value, and thespatial distribution of the polarity in each frame is not problematic.Accordingly, from the perspective of low power consumption or the like,it is preferable to reduce the number of times of polarity inversion ofthe data signal Vda supplied from the source bus line; that is, tolengthen the period of polarity inversion. For example, as illustratedin FIG. 18E, the period of polarity inversion may be set to 10 H (suchthat polarity inversion occurs every 5 H). Of course, in a case wherethe number of antenna units connected to each source bus line (typicallyequal to the number of gate bus lines) is m, the period of polarityinversion of the data signal Vda may be 2 m·H (polarity inversion occurseach m·H). The period of polarity inversion of the data signal Vda maybe equal to 2 frames (a polarity inversion occurs each frame).

In addition, the polarity of the data signal Vda supplied from all thesource bus lines may be the same. Accordingly, for example, in aparticular frame, a positive polarity data signal Vda may be suppliedfrom all the source bus lines, and in the next frame, a negativepolarity data signal Vda may be supplied from all the source bus lines.

Alternatively, the polarities of the data signals Vda supplied from theadjacent source bus lines may be opposite to each other. For example, ina particular frame, a positive polarity data signal Vda is supplied fromodd-numbered source bus lines, and a negative polarity data signal Vdamay be supplied from even-numbered source bus lines. Then, in the nextframe, the negative polarity data signal Vda is supplied from theodd-numbered source bus lines, and the positive polarity data signal Vdais supplied from the even-numbered source bus lines. In the LCD panels,such a driving method is referred to as source line inversion driving.In a case where the data signals Vda supplied from adjacent source busline are made to have opposite polarity, by connecting(short-circuiting) adjacent source bus lines to each other beforeinverting the polarity of the data signals Vda supplied between frames,it is possible to cancel electric charges stored in the liquid crystalcapacitance between adjacent columns. Accordingly, an advantage can beobtained such that the amount of electric charge supplied from thesource bus line in each frame can be reduced.

As illustrated in FIG. 18F, the voltage Vidc of the slot electrode is,for example, a DC voltage, and is typically a ground potential. Sincethe capacitance value of the capacitance (liquid crystal capacitance andauxiliary capacitance) of the antenna units is greater than thecapacitance value of the pixel capacitance of the LCD panel (forexample, about 30 times in comparison with 20-inch LCD panels), there isno affect from the pull-in voltage due to the parasitic capacitance ofthe TFT, and even in a case where the voltage Vide of the slot electrodeis the ground potential and the data signal Vda is a positive ornegative symmetrical voltage with reference to the ground potential, thevoltage supplied to the patch electrode is a positive and negativesymmetrical voltage. In the LCD panels, although the positive andnegative symmetrical voltages are applied to the pixel electrode byadjusting the voltage (common voltage) of the counter electrode inconsideration of the pull-in voltage of the TFT, this is not necessaryfor the slot voltage of the scanning antenna, and ground potential maybe used. Also, although not illustrated in FIG. 18A to FIG. 18G, thesame voltage as the slot voltage Vide is supplied to the CS bus line.

Since the voltage applied to the liquid crystal capacitance of eachantenna unit is the voltage of the patch electrode with respect to thevoltage Vidc (FIG. 18F) of the slot electrode (that is, the voltage ofthe data signal Vda illustrated in FIG. 18E), when the slot voltage Vidcis the ground potential, as illustrated in FIG. 18G, the voltagecoincides with the waveform of the data signal Vda illustrated in FIG.18E.

The waveform of the signal used for driving the scanning antenna is notlimited to the above example. For example, as described below withreference to FIG. 19A to FIG. 19E and FIG. 20A to FIG. 20E, a Viachaving an oscillation waveform may also be used as the voltage of theslot electrode.

For example, signals such as those exemplified in FIG. 19A to FIG. 19Ecan be used. In FIG. 19A to FIG. 19E, although the waveform of thescanning signal Vg supplied to the gate bus line is omitted, thescanning signal Vg described with reference to FIG. 18A to FIG. 18C isalso used here.

As illustrated in FIG. 19A, similar to that illustrated in FIG. 18E, acase where the waveform of the data signal Vda is inverted in polarityat a 10H period (every 5 H) will be exemplified. Here, a case where theamplitude is the maximum value |Vda_(max)| is illustrated as the datasignal Vda. As described above, the waveform of the data signal Vda maybe inverted in polarity at a two frame period (each frame).

Here, as illustrated in FIG. 19C, the voltage Viac of the slot electrodeis an oscillation voltage such that the polarity of the voltage Viac ofthe slot electrode is opposite to the polarity of the data signal Vda(ON), and the oscillation period of the slot electrode is the same asthat of data signal Vda (ON). The amplitude of the voltage Viac of theslot electrode is equal to the maximum value |Vda_(max)| of theamplitude of the data signal Vda. That is, the slot voltage Viac is setto a voltage that oscillates between −Vda_(max) and +Vda_(max) with thesame period of polarity inversion as that of the data signal Vda (ON)and opposite polarity (the phase differs by 1800).

Since the voltage Vie applied to the liquid crystal capacitance of eachantenna unit is the voltage of the patch electrode with respect to thevoltage Viac of the slot electrode (FIG. 19C) (that is, the voltage ofthe data signal Vda (ON) illustrated in FIG. 19A), when the amplitude ofthe data signal Vda oscillates at ±Vda_(max), the voltage applied to theliquid crystal capacitance has a waveform that oscillates with anamplitude twice Vda_(max) as illustrated in FIG. 19D. Accordingly, themaximum amplitude of the data signal Vda required to make the maximumamplitude of the voltage Vie applied to the liquid crystalcapacitance±Vda_(max) is +Vda_(max)/2.

Since the maximum amplitude of the data signal Vda can be halved byusing such a slot voltage Viac, there is the advantage that ageneral-purpose driver IC with a breakdown voltage of 20 V or less canbe used as a driver circuit for outputting the data signal Vda, forexample.

Note that, as illustrated in FIG. 19E, to make the voltage Vlc (OFF)applied to the liquid crystal capacitance of each antenna unit zero, asillustrated in FIG. 19B, it may be preferable for the data signal Vda(OFF) to have the same waveform as that of the slot voltage Viac.

Consider, for example, a case where the maximum amplitude of the voltageVlc applied to the liquid crystal capacitance is ±15 V. When the Vidcillustrated in FIG. 18F is used as the slot voltage and Vidc=0 V, themaximum amplitude of Vda illustrated in FIG. 18E becomes ±15 V. Incontrast, when the Viac illustrated in FIG. 19C is used as the slotvoltage and the maximum amplitude of Viac is ±7.5 V, the maximumamplitude of Vda (ON) illustrated in FIG. 19A becomes ±7.5 V.

When the voltage Vlc applied to the liquid crystal capacitance is 0 V,the Vda illustrated in FIG. 18E may be set to 0 V, and the maximumamplitude of the Vda (OFF) illustrated in FIG. 19B may be set to ±7.5 V.

In a case where the Viac illustrated in FIG. 19C is utilized, theamplitude of the voltage Vlc applied to the liquid crystal capacitanceis different from the amplitude of Vda, and therefore appropriateconversions are necessary.

Signals such as those exemplified in FIG. 20A to FIG. 20E can also beused. The signals illustrated in FIG. 20A to FIG. 20E are the same asthe signals illustrated in FIG. 19A to FIG. 19E in that the voltage Viacof the slot electrode is an oscillation voltage such that theoscillation phase thereof is shifted by 180° from the oscillation phaseof the data signal Vda (ON) as illustrated in FIG. 20C. However, asillustrated in each of FIG. 20A to FIG. 20C, all of the data signals Vda(ON), Vda (OFF) and the slot voltage Viac are voltages oscillatingbetween 0 V and a positive voltage. The amplitude of the voltage Viac ofthe slot electrode is equal to the maximum value |Vda_(max)| of theamplitude of the data signal Vda.

When such a signal is utilized, the driving circuit only needs to outputa positive voltage, which contributes to cost reduction. As describedabove, even in a case where a voltage oscillating between 0 V and apositive voltage is used, as illustrated in FIG. 20D, the polarity ofthe voltage Vic (ON) applied to the liquid crystal capacitance isinverted. In the voltage waveform illustrated in FIG. 20D, +(positive)indicates that the voltage of the patch electrode is higher than theslot voltage, and − (negative) indicates that the voltage of the patchelectrode is lower than the slot voltage. That is, the direction(polarity) of the electric field applied to the liquid crystal layer isinverted similarly to the other examples. The amplitude of the voltageVic (ON) applied to the liquid crystal capacitance is Vda_(max).

Note that, as illustrated in FIG. 20E, to make the voltage Vlc (OFF)applied to the liquid crystal capacitance of each antenna unit zero, asillustrated in FIG. 20B, it may be preferable for the data signal Vda(OFF) to have the same waveform as that of the slot voltage Viac.

The driving method described with reference to FIG. 19A to FIG. 19E andFIG. 20A to FIG. 20E of oscillating (inverting) the voltage Viac of theslot electrodes corresponds to a driving method of inverting the countervoltage in the driving method of the LCD panels (sometimes referred toas a “common inversion drive”). In the LCD panels, since the flickercannot be sufficiently suppressed, the common inversion drive is notutilized. In contrast, in the scanning antennas, since the flicker doesnot matter, the slot voltage can be inverted. Oscillation (inversion) isperformed in each frame, for example (the 5H in FIG. 19A to FIG. 19E andFIG. 20A to FIG. 20E is set to 1 V (vertical scanning period or frame)).

In the above description, although an example of the voltage Viac of theslot electrode is described in which one voltage is applied; that is, anexample in which a common slot electrode is provided for all patchelectrodes, the slot electrode may be divided corresponding to one rowor two or more rows of the patch electrode. Here, a row refers to a setof patch electrodes connected to one gate bus line with a TFTtherebetween. By dividing the slot electrode into a plurality of rowportions in this way, the polarities of the voltages of the respectiveportions of the slot electrode can be made independent from each other.For example, in a freely-selected frame, the polarity of the voltageapplied to the patch electrodes can be inverted between the patchelectrodes connected to adjacent gate bus lines. In this way, it ispossible to perform row inversion in which the polarity is inverted notonly for each single row (1H inversion) of the patch electrode, but alsom row inversion (mH inversion) in which the polarity is inverted forevery two or more rows. Of course, row inversion and frame inversion canbe combined.

From the viewpoint of simplicity of driving, it is preferable that thepolarity of the voltage applied to the patch electrode be the same inany frame, and the polarity be inverted every frame.

Example of Connection of Antenna Unit Array, Gate Bus Line, and SourceBus Line In the scanning antenna according to the embodiments of thedisclosure, the antenna units are arranged concentrically, for example.

For example, in a case where the antenna units are arranged in mconcentric circles, one gate bus line is provided for each circle, forexample, such that a total of m gate bus lines is provided. For example,assuming that the outer diameter of the transmission and/or receptionregion R1 is 800 mm, m is 200, for example. Assuming that the innermostgate bus line is the first one, n (30, for example) antenna units areconnected to the first gate bus line and nx (620, for example) antennaunits are connected to the mth gate bus line.

In such an arrangement, the number of antenna units connected to eachgate bus line is different. In addition, although m antenna units areconnected to a number n of the source bus lines that are also connectedto the antenna units constituting the innermost circle, among the nxnumber of source bus lines connected to nx number antenna units thatconstitute the outermost circle, the number of antenna units connectedto other source bus lines is less than m.

In this way, the arrangement of antenna units in the scanning antenna isdifferent from the arrangement of pixels (dots) in the LCD panel, andthe number of connected antenna units differs depending on the gate busline and/or source bus line. Accordingly, in a case where thecapacitances (liquid crystal capacitances+auxiliary capacitances) of allthe antenna units are set to be the same, depending on the gate bus lineand/or the source bus line, the electrical loads of the antenna unitsconnected thereto differ. In such a case, there is a problem wherevariations occur in the writing of the voltage to the antenna unit.

Accordingly, to prevent this, the capacitance value of the auxiliarycapacitance is preferably adjusted, or the number of antenna unitsconnected to the gate bus line and/or the source bus line is preferablyadjusted, for example, to make the electrical loads of the antenna unitsconnected to the gate bus lines and the source bus lines substantiallythe same.

As described above, the scanning antenna according to the embodiment ofthe disclosure uses a nematic liquid crystal material having largedielectric anisotropies Δε_(M) with respect to microwaves (birefringenceindex Δn with respect to visible light). As the liquid crystal materialhaving large dielectric anisotropies Δε_(M) in the microwave region, aliquid crystal material containing a liquid crystal molecule having anisothiocyanate group (—NCS) is used. In general, since the liquidcrystal material is a mixture of a plurality of types of liquid crystalmolecules (liquid crystal compounds), all liquid crystal moleculescontained in the liquid crystal material need not have an isothiocyanategroup.

The isothiocyanate group is included in the liquid crystal molecule asan atomic group represented by the following chemical formula (Formula1), for example.

The holding rate of the voltage applied to the liquid crystalcapacitance is low due to the low specific resistance of the liquidcrystal material containing a liquid crystal molecule having anisothiocyanate group. When the liquid crystal material deteriorates, thespecific resistance further decreases, and the voltage holding rate(sometimes abbreviated as “VHR”) further decreases. A decrease of theVHR prevents the liquid crystal molecules from being aligned in apredetermined direction (that is, a desired phase difference cannot begiven to the microwave), thereby deteriorating the antennacharacteristics.

The inventor of the disclosure has discovered that the followingmechanism acts as one of reasons for the deterioration of the VHRoccurring when using a liquid crystal material containing liquid crystalmolecules each having an isothiocyanate group.

The carbon atom in the isothiocyanate group has high electrophilicityand positively charges due to its polarization. Thus, a highly activemetal (such as Cu or Al), its oxide, or its ion allow the carbon atom tobe readily ionized (C²⁺) as illustrated in Formula 2, causing adeterioration of the VHR. Although Formula 2 represents a reactionformula in which an isothiocyanate group is ionized by copper (Cu), itis conceivable that aluminum (Al) may also cause an ionization by asimilar reaction.

The inventor has found that through conducting various experiments, aswill be described later by partially demonstrating the experimentalexamples, a compound having an atomic group forming a coordinate bondwith Cu or Al (hereinafter referred to as “coordination bond compound”)formed to be in contact with the patch electrode and the slot electrodesuppresses an isocyanate group from being ionized by Cu or Al. The resinlayer may be formed of an alignment film or may be additionally formedbetween an alignment film and an electrode. In a case when the patchelectrode and the slot electrode are covered with an insulating film,the resin layer may be formed on the insulating film. Coordination bondcompounds have, for example, an amide bond and a benzene ring (forexample, as a phenyl group or a phenylene group). The coordination bondcompounds may be, for example, oxalic acid derivatives. Hereinafter,there will be described an example of the coordination bond compounds,which is, but not limited to, oxalic acid derivatives. The resin layermay contain several types of coordination bond compounds. In addition,the resin layer provided on the patch electrode side may contain adifferent type of coordination bond compound from the resin layerprovided on the slot electrode side.

As the coordination bond compounds, oxalic acid derivatives of thefollowing compounds 1 to 5 are exemplified. The molecular weights of thecompounds 1 to 5 are 294, 696, 256, 526, and 490, respectively. Themolecular weight of the coordination bond compounds is preferably 1000or less. When the molecular weight is greater than 1000, the mobilityand diffusibility of the molecule may be lowered, causing the formationof coordination bonds to be suppressed. Also, a rigid structure as inpolyimides also suppresses the formation of coordination bonds.Accordingly, coordination bond compounds having a structure singlebonded to a benzene ring are preferred as exemplified in the compounds 1to 5 of the following Formula 3.

Oxalic acid derivatives form coordination bonds (form complexes) with Cuions or Al ions, suppressing an isothiocyanate group from being reactedwith these ions. This allows the probability of generation of ions bythe reaction illustrated in Formula 2 to be drastically reduced, therebysuppressing the VHR from being reduced.

The amount of the oxalic acid derivatives contained in the resin film ispreferably as large as possible in order to increase the probability offorming coordination bonds (complexes). In addition, in a case when analignment film is used as the resin layer, it is preferred that theoxalic acid derivatives are unevenly distributed on the side close tothe electrode.

As the alignment film, an alignment film containing polyimide and/orpolyamic acid (also referred to as “polyamide acid”) is widely used. Byheating and imidizing the polyamic acid is produced polyimide. Thepolyamic acid is not necessarily fully imidized (imidizationratio=100%), but the imidization ratio can be adjusted depending onthermal condition (temperature and time). Herein, the alignment filmcontaining polyimide and/or polyamic acid is referred to as“polyimide-based alignment film”, and the material for forming“polyimide-based alignment film” is referred to as “polyimide-basedalignment film material”.

In a case when an alignment film including a double-layer structure isused as the alignment film, it is preferred to adopt a configuration inwhich a large amount of oxalic acid derivatives is contained in thelower layer (layer closer to the electrode). For example, if a polyamicacid remains on the alignment film, an advantage of reducing theresidual DC (for example, WO 2010/047011) is provided. By adjusting thethermal condition using an alignment film material containing polyamicacid and polyimide, a polyamic acid-rich layer can be formed at thelower layer (electrode side) while a polyimide-rich layer at the upperlayer (liquid crystal layer side). Of course, the polyamic acid-richlayer at the lower layer may be separately formed from thepolyimide-rich layer at the upper layer. The lower layer preferablycontains a large amount of oxalic acid derivatives. While the upperlayer (layer closer to the liquid crystal layer) may not contain oxalicacid derivatives.

A resin layer containing oxalic acid derivatives, which is formedseparately from the alignment film, may be formed, for example, byremoving the solvent from a solution containing a soluble polymer andoxalic acid derivatives. As the soluble polymer, for example, an acrylicpolymer may be suitably used. A thermosetting resin may also be used. Asthe thermosetting resin, for example, acrylate monomers (includingacrylate oligomers) may be suitably used. A thermal polymerizationinitiator may be further added to the acrylate monomers as necessary.Note that, in this specification, acrylic and acrylate are used torepresent including methacrylic and methacrylate, respectively.

Incidentally, the amount of the oxalic acid derivatives contained in theresin layer is preferably set at 30 mass % or less with respect to theresin. If the amount is greater than 30 mass %, the film formingproperties may be deteriorated. The resin layer containing the oxalicacid derivatives may be formed using a known coating method (forexample, a slot coating method) and/or a printing method (for example, ascreen printing method or an ink jet method).

Hereinafter, a structure of a scanning antenna including an alignmentfilm that includes a resin layer containing coordination bond compounds(hereinafter, oxalic acid derivatives) and a method of manufacturing thescanning antenna will be described. Note that the structure of theliquid crystal panel in the scanning antenna will be described below.The liquid crystal panel includes a TFT substrate, a slot substrate, anda liquid crystal layer LC provided therebetween, and liquid crystalpanels 10A, 100B, 100C, and 100D exemplified below are each featured inthe structure of the alignment film and the method of forming thealignment film. The liquid crystal panels 100A, 100B, 100C, and 100D maybe applied to any one of the above-described scanning antennas. In FIG.21 to FIG. 24 illustrating the liquid crystal panels 100A, 100B, 100C,and 100D, common reference numbers are denoted to structural elementscommon to the previous drawings, and no descriptions for such structuralelements may be provided below.

FIG. 21 is a schematic cross-sectional view of the liquid crystal panel100A. The liquid crystal panel 100A includes a TFT substrate 101A, aslot substrate 201A, and a liquid crystal layer LC providedtherebetween. The patch electrode 15 of the TFT substrate 101A and theslot electrode 55 of the slot substrate 201A are covered with alignmentfilms 32A and 42A, respectively. The patch electrode 15 and the slotelectrode 55 are each independently formed of, for example, Al or Cu.The alignment films 32A and 42A are formed of a polyimide-basedalignment film material each independently selected, and each of thefilms contains coordination bond compounds.

FIG. 22 is a schematic cross-sectional view of the liquid crystal panel100B. In the liquid crystal panel 100B, the patch electrode 15 of theTFT substrate 101B and the slot electrode 55 of the slot substrate 201Bare covered with alignment films 32B and 42B, respectively.

The alignment films 32B and 42B include polyamic acid (-rich) layers 32a and 42 a at the lower layer (substrate side) and polyimide (-rich)layers 32 b and 42 b at the upper layer (liquid crystal layer side). Thepolyamic acid (-rich) layers 32 a and 42 a at the lower layer containscoordination bond compounds, while the upper polyimide (-rich) layers 32b and 42 b contains no coordination bond compounds.

FIG. 23 is a schematic cross-sectional view of the liquid crystal panel100C. In the liquid crystal panel 100C, the patch electrode 15 of theTFT substrate 101C and the slot electrode 55 of the slot substrate 201Care covered with resin layers 34 and 44 containing coordination bondcompounds, respectively. The resin layers 34 and 44 are covered withalignment films 32C and 44C, respectively.

FIG. 24 is a schematic cross-sectional view of the liquid crystal panel100D. In the liquid crystal panel 100D, the patch electrode 15 of theTFT substrate 101D and the slot electrode 55 of the slot substrate 201Dare covered with a second insulating layer 27 and a fourth insulatinglayer 58, respectively, and the second insulating layer 27 and thefourth insulating layer 58 are covered with alignment films 32A and 42A,respectively. That is, the liquid crystal panel 100D corresponds to theliquid crystal panel 100A further provided with the second insulatingfilm 17 and the fourth insulating film 58 covering the patch electrode15 and the slot electrode 55.

Similarly, the second insulating film 17 and the fourth insulating film58 may be provided to cover the patch electrode 15 and the slotelectrode 55 in the liquid crystal panels 100B and 100C.

EXPERIMENTAL EXAMPLES

Hereinafter, Experimental Examples are described to explain that aprovision of a resin layer containing coordination bond compoundssuppresses the deterioration of the antenna characteristics of thescanning antenna occurring when using a liquid crystal materialcontaining liquid crystal molecules each having an isothiocyanate group.

Experimental Example 1

As illustrated in the Table 1 below, test panels (Samples 2 to 4)including the structure of the liquid crystal panel 100A illustrated inFIG. 21 were prepared varying mass % of the oxalic acid derivatives ofthe compound 1 to be blended into the polyimide-based alignment filmmaterial. The patch electrode 15 and the slot electrode 55 were eachformed with an Al layer.

Polyimide alignment film materials were used in which X in thestructural formulas (1) and (2) denoted in Formula 4 is represented bythe following Formula 5 and Y is represented by the following Formula 6.The initial imidization ratio was approximately 50%. The degree ofpolymerization m determined by GPC was within the range of approximatelyfrom 50 to 400.

Samples 2, 3, and 4 were prepared by liquid crystal panels in which thealignment films are formed using polyimide-based alignment filmmaterials into which the oxalic acid derivatives of the compound 1 areblended by 10 mass %, 20 mass %, and 30 mass % with respect to thealignment film material. Sample 1 was prepared by a liquid crystal panelin which the alignment film is formed using a polyimide-based alignmentfilm material not containing the compound 1. The smaller theintroduction amount (mass %) of the oxalic acid derivatives with respectto the polyimide-based alignment film material, although the filmforming properties are maintained, the less the effect of improving thereliability due to the formation of the complexes. Meanwhile, the largerthe introduction amount of the oxalic acid derivatives, the higher theeffect of improving the reliability due to the formation of thecomplexes, however, if the introduction amount exceeds 30 mass % withrespect to the resin, the film may become opaque. When the film becomesopaque, for example, a film peeling may occur at the time of rubbing,exerting influence on the alignment properties of the liquid crystal.

Alignment film solutions (solid content concentration: 3 mass %) inwhich each of the alignment film materials described above is dissolvedin a solvent (mixed solvent of NMP and γ-butyl lactone) were preparedand applied onto a TFT substrate and a slot substrate. Subsequently, atemporary baking was carried out at 80° C. for 2 minutes, followed bythe final baking at 200° C. for 40 minutes. After performing a rubbingtreatment as an alignment treatment, the two substrates were bondedtogether using a thermosetting sealing material. Note that the cell gap(=the thickness of the liquid crystal layer) was adjusted to 3.0 μm by aspacer. The sealing material was cured by heating at 150° C. for 40minutes. A liquid crystal material having liquid crystal molecules eachhaving an isothiocyanate group was injected. Lastly, the injection portwas sealed with an ultraviolet light curable sealing material to preparetest panels.

The voltage holding rate (VHR) was evaluated before and after thehigh-temperature test. The VHR was measured, using a 6254 type VHRmeasurement system available from Toyo Technica Co., Ltd., by applying arectangular wave having an amplitude of ±1 V and a frequency of 60 Hz.The measurement temperature was set at 70° C. The high-temperature testwas conducted in a thermostat at 90° C. for 24 hours. The values of theVHR before and after the high-temperature test are listed in Table 1.

TABLE 1 After high- Coordination bond compound 1 Initial temperature inAlignment film 1 stage test Contained amount (mass %) VHR (%) VHR (%)Sample 1 0 93 54 Sample 2 10 92 66 Sample 3 20 92 75 Sample 4 30 93 75

In Sample 1 not containing oxalic acid derivatives in the alignmentfilm, the VHR was decreased to 54% after the high-temperature test. Theelectrode formed of an Al layer conceivably leads to, like the case ofCu described above, an ionization of Al, and an ionization of anisothiocyanate group caused by the reaction of Al and isothiocyanategroup.

Samples 2 to 4 containing the oxalic acid derivatives of the compound 1maintains, even after the high-temperature test, the VHR at a value of65% or more and Samples 3 and 4 containing 20 mass % or more of thecompound 1 maintains the VHR at a value of 75%. It is conceivable thatthe oxalic acid derivatives contained in the alignment film formcoordination bonds with Al (ions) to inactivate the Al, therebysuppressing the ionization of the isothiocyanate group and preventingthe decrease of the VHR.

Experimental Example 2

Test panels (Samples 5 to 8) including the structure of the liquidcrystal panel 100B illustrated in FIG. 22 were prepared. The patchelectrode 15 and the slot electrode 55 were each formed with an Allayer. A polyimide-based alignment film material having the basicstructure as in Experimental Example 1 was used. However, to form thelower layer of the alignment film was used an alignment film material ofthe imidization ratio of 0%, that is, an alignment film materialconsisting only of the polyamic acid of the structural formula (2).

Samples 6, 7, and 8 were prepared by liquid crystal panels in which thealignment films are formed using alignment film materials of a polyamicacid (imidization ratio 0%) into which the oxalic acid derivatives ofthe compound 2 are blended by 10 mass %, 20 mass %, and 30 mass % withrespect to the alignment film material. Sample 5 was prepared by aliquid crystal panel in which the alignment film is formed using apolyimide-based alignment film material not containing the compound 2.

Alignment film solutions (solid content concentration: 3 mass %) inwhich each of the alignment film materials for the lower layersdescribed above is dissolved in a solvent (mixed solvent of NMP, butylcellosolve, and γ-butyl lactone) were prepared and applied onto a TFTsubstrate and a slot substrate. Subsequently, a temporary baking wascarried out at 80° C. for 2 minutes, followed by the final baking at160° C. for 40 minutes.

Next, as alignment film materials for the upper layers, alignment filmsolutions (solid content concentration: 3 mass %) in which apolyimide-based alignment film material (not containing oxalic acidderivatives) of the imidization ratio 50% is dissolved in a solvent(mixed solvent of NMP and butyl cellosolve) were prepared and appliedonto the lower layers formed as described above, and to which atemporary baking was carried out at 80° C. for 2 minutes, followed bythe final baking at 200° C. for 40 minutes. After performing a rubbingtreatment as an alignment treatment, test panels were prepared in thesame manner as in Experimental Example 1.

The test panels (Samples 5 to 8) thus prepared were evaluated in thesame manner as in Experimental Example 1. The results are listed inTable 2 below.

TABLE 2 After high- Coordination bond compound 2 in Initial temperaturethe lower layer of the alignment stage test film Contained amount (mass%) VHR (%) VHR (%) Sample 5 0 95 59 Sample 6 10 93 76 Sample 7 20 95 80Sample 8 30 95 84

In Sample 5 not containing the oxalic acid derivatives of the compound 2in the lower layers of the alignment film, the VHR was decreased to 60%or less after the high-temperature test. Meanwhile, in Samples 6 to 8containing the oxalic acid derivatives of the compound 2, the VHRs weremaintained at a high value of 75% or more even after thehigh-temperature test, and in Samples 7 and 8 containing the compound 2at 20 mass % or more, the VHRs were maintained at a high value of 85% ormore. This proves that oxalic acid derivatives are blended into only thelower layers (electrode side) of the alignment film including thedouble-layer structure, whereby the VHR is effectively improved.

Experimental Example 3

Test panels (Samples 11 to 13) including the structure of the liquidcrystal panel 100C illustrated in FIG. 23 were prepared. A test panel(Sample 9) not including the resin layers 34 and 44 and a test panel(Sample 10) provided with a resin layer not including oxalic acidderivatives were also prepared for comparison. The patch electrode 15and the slot electrode 55 were formed with a Cu layer.

Solutions were prepared by blending into NMP solutions of ethyl acrylatepolymer, 10 mass %, 20 mass %, and 30 mass % of the oxalic acidderivatives of the compound 1 with respect to the polymer. Each of thesolutions was applied onto a TFT substrate and a slot substrate.Subsequently, a baking was carried out at 180° C. for 15 minutes to formthe resin layers 34 and 44 containing the compound 1.

Next, alignment film solutions (solid content concentration: 3 mass %)in which a polyimide-based alignment film material (not containingoxalic acid derivatives) is dissolved in a solvent (mixed solvent ofNMP, butyl cellosolve, and γ-butyl lactone) were prepared and appliedonto the resin layers formed as described above, and to which atemporary baking was carried out at 80° C. for 2 minutes, followed bythe final baking at 230° C. for 40 minutes. After performing a rubbingtreatment as an alignment treatment, test panels were prepared in thesame manner as in Experimental Example 1.

The test panels (Samples 9 to 13) thus prepared were evaluated in thesame manner as in Experimental Example 1. The results are listed inTable 3 below.

TABLE 3 Coordination bond After high- Acrylic compound 1 in AcrylicInitial temperature resin resin layer Contained stage test layer amount(mass %) VHR (%) VHR (%) Sample 9 No — 93 50 Sample 10 Yes  0 94 51Sample 11 Yes 10 93 60 Sample 12 Yes 20 93 70 Sample 13 Yes 30 94 71

In Sample 9 not including a resin layer and in Sample 10 including aresin layer but not including oxalic acid derivatives, the VHRs weredecreased to nearly 50% after the high-temperature test. Meanwhile, inSamples 11 to 13 containing the oxalic acid derivatives of the compound1, the VHRs are maintained at a high value of 60% or more even after thehigh-temperature test, and in Samples 12 and 13 containing the compound1 at 20 mass % or more, the VHRs are maintained at a high value of 70%or more. It is conceivable that the oxalic acid derivatives contained inthe resin layer form coordination bonds with Cu (ions) to inactivate theCu, thereby suppressing the ionization of the isothiocyanate group andpreventing the decrease of the VHR.

Experimental Example 4

Test panels (Samples 15 to 17) including the structure of the liquidcrystal panel 100D illustrated in FIG. 24 were prepared. A test panel(sample 14) provided with a resin layer not containing oxalic acidderivatives in the alignment film was also prepared for comparison. Thepatch electrode 15 and the slot electrode 55 were formed with a Culayer. The insulating layers 17 and 58 covering the patch electrode 15and the slot electrode 55 were formed with a SiN layer (thickness 200nm).

A polyimide-based alignment film material (imidization ratio 50%) as inExperimental Example 1 was used. Samples 15, 16, and 17 were prepared byliquid crystal panels in which the alignment films are formed usingpolyimide-based alignment film materials into which the oxalic acidderivatives of the compound 2 are blended by 10 mass %, 20 mass %, and30 mass % with respect to the alignment film material. Sample 14 wasprepared by a liquid crystal panel in which the alignment film is formedusing a polyimide-based alignment film material not containing thecompound 2.

Alignment film solutions (solid content concentration: 3 mass %) inwhich each of the alignment film materials described above is dissolvedin a solvent (mixed solvent of NMP, butyl cellosolve, and γ-butyllactone) were prepared and applied onto a TFT substrate and a slotsubstrate. Subsequently, a temporary baking was carried out at 80° C.for 2 minutes, followed by the final baking at 230° C. for 40 minutes.After performing a rubbing treatment as an alignment treatment, testpanels were prepared in the same manner as in Experimental Example 1.

The test panels (Samples 14 to 17) thus prepared were evaluated in thesame manner as in Experimental Example 1. The results are listed inTable 4 below.

TABLE 4 After high- Coordination bond compound 2 Initial temperature inAlignment film stage test Contained amount (mass %) VHR (%) VHR (%)Sample 14 0 96 78 Sample 15 10 96 89 Sample 16 20 96 91 Sample 17 30 9691

In view of the result of Sample 14, it can be recognized that aconfiguration in which the patch electrode and the slot electrode arecovered with an insulating layer formed from an SiN layer makes itpossible to maintain, even when using an alignment film not containingoxalic acid derivatives, the VHR at a high value of 78% after thehigh-temperature test. In Samples 15 to 17 containing the oxalic acidderivatives of the compound 2, the VHRs are approximately 90% after thehigh-temperature test, thereby further improving the reliability.

As described above, the scanning antenna according to the embodiment ofthe disclosure suppresses the deterioration of the antennacharacteristic occurring when using a liquid crystal material includingliquid crystal molecules each having an isothiocyanate group.

The scanning antenna according to the embodiments of the disclosure ishoused in a plastic housing as necessary, for example. It is preferableto use a material having a small dielectric constant ε_(M) that does notaffect microwave transmission and/or reception in the housing. Inaddition, the housing may include a through-hole provided in a portionthereof corresponding to the transmission and/or reception region R1.Furthermore, the housing may include a light blocking structure suchthat the liquid crystal material is not exposed to light. The lightblocking structure is, for example, provided so as to block light thatpropagates through the dielectric substrate 1 and/or 51 from the sidesurface of the dielectric substrate 1 of the TFT substrate 101 and/orthe side surface of the dielectric substrate 51 of the slot substrate201 and is incident upon the liquid crystal layer. A liquid crystalmaterial having a large dielectric anisotropy Δε_(M) may be prone tophotodegradation, and as such it is preferable to shield not onlyultraviolet rays but also short-wavelength blue light from among visiblelight. By using a light-blocking tape such as a black adhesive tape, forexample, the light blocking structure can be easily formed in necessarylocations.

INDUSTRIAL APPLICABILITY

The embodiments according to the disclosure are used, for example, for ascanning antenna for satellite communication or satellite broadcastinginstalled on a moving body (for example, a ship, an airplane, or a car)and a method of manufacturing the scanning antenna.

REFERENCE SIGNS LIST

-   1 Dielectric substrate-   2 Base insulating film-   3 Gate electrode-   4 Gate insulating layer-   5 Semiconductor layer-   6D Drain contact layer-   6S Source contact layer-   7D Drain electrode-   7S Source electrode-   7 p Source connection wiring line-   11 First insulating layer-   15 Patch electrode-   15 p Patch connection section-   17 Second insulating layer-   18 g, 18 s, 18 p Opening-   19 g Gate terminal upper connection section-   19 p Transfer terminal upper connection section-   19 s Source terminal upper connection section-   21 Alignment mark-   23 Protective conductive layer-   32A, 32B, 32C Alignment film-   34 Resin layer-   42A, 42B, 42C Alignment film-   44 Resin layer-   51 Dielectric substrate-   52 Third insulating layer-   54 Dielectric layer (air Layer)-   55 Slot electrode-   55L Lower layer-   55M Main layer-   55U Upper layer-   55 c Contact surface-   57 Slot-   58 Fourth insulating layer-   60 Upper connection section-   65 Reflective conductive plate-   67 Adhesive layer-   68 Heater resistive film-   70 Power supply device-   71 Conductive beads-   72 Power feed pin-   73 Sealing portion-   101, 102, 103, 104 TFT substrate-   201, 203 Slot substrate-   1000 Scanning antenna-   CH1, CH2, CH3, CH4, CH5, CH6 Contact hole-   GD Gate driver-   GL Gate bus line-   GT Gate terminal section-   SD Source driver-   SL Source bus line-   ST Source terminal section-   PT Transfer terminal section-   IT Terminal section-   LC Liquid crystal layer-   R1 Transmission and/or reception region-   R2 Non-transmission and/or reception region-   Rs Seal region-   U, U1, U2 Antenna unit, Antenna unit region

1. A scanning antenna, in which a plurality of antenna units arearranged, comprising: a TFT substrate including a first dielectricsubstrate, a plurality of TFTs supported on the first dielectricsubstrate, a plurality of gate bus lines, a plurality of source buslines, a plurality of patch electrodes, and a first alignment filmcovering the plurality of patch electrodes; a slot substrate including asecond dielectric substrate, a slot electrode formed on a first mainsurface of the second dielectric substrate, the slot electrode includinga plurality of slots arranged corresponding to the plurality of patchelectrodes, and a second alignment film covering the slot electrode; aliquid crystal layer provided between the TFT substrate and the slotsubstrate, the liquid crystal layer containing a liquid crystal moleculehaving an isothiocyanate group; and a reflective conductive platedisposed to face a second main surface on an opposite side to the firstmain surface of the second dielectric substrate with a dielectric layerinterposed therebetween, wherein the plurality of patch electrodes andthe slot electrodes are each formed of a Cu layer or an Al layer, andwherein the first alignment film and the second alignment film eachinclude a compound having an atomic group forming a coordinate bond withCu or Al.
 2. The scanning antenna according to claim 1, wherein at leastone of the first alignment film and the second alignment film include anupper layer close to the liquid crystal layer and a lower layer, whereinthe compound is contained in the lower layer.
 3. A scanning antenna, inwhich a plurality of antenna units are arranged, comprising: a TFTsubstrate including a first dielectric substrate, a plurality of TFTssupported on the first dielectric substrate, a plurality of gate buslines, a plurality of source bus lines, a plurality of patch electrodes,and a first alignment film covering the plurality of patch electrodes; aslot substrate including a second dielectric substrate, a slot electrodeformed on a first main surface of the second dielectric substrate, theslot electrode including a plurality of slots arranged corresponding tothe plurality of patch electrodes, and a second alignment film coveringthe slot electrode; a liquid crystal layer provided between the TFTsubstrate and the slot substrate, the liquid crystal layer containing aliquid crystal molecule having an isothiocyanate group; and a reflectiveconductive plate disposed to face a second main surface on an oppositeside to the first main surface of the second dielectric substrate with adielectric layer interposed therebetween, wherein the plurality of patchelectrodes and the slot electrodes are each formed of a Cu layer or anAl layer, and wherein between the first alignment film and the pluralityof patch electrodes and between the second alignment film and the slotelectrode are each independently provided with a resin layer containinga compound having an atomic group forming a coordinate bond with Cu orAl.
 4. The scanning antenna according to claim 3, wherein the resinlayer includes a cured acrylate.
 5. The scanning antenna according toclaim 1, wherein the compound has an amide bond and a benzene ring. 6.The scanning antenna according to claim 1, wherein the compound has amolecular weight of less than
 1000. 7. The scanning antenna according toclaim 1, wherein an insulating layer covering the plurality of patchelectrodes and a further insulating layer covering the slot electrodeare provided.
 8. The scanning antenna according to claim 3, wherein thecompound has an amide bond and a benzene ring.
 9. The scanning antennaaccording to claim 3, wherein the compound has a molecular weight ofless than
 1000. 10. The scanning antenna according to claim 3, whereinan insulating layer covering the plurality of patch electrodes and afurther insulating layer covering the slot electrode are provided.